diff --git a/.github/workflows/phpunit-tests.yml b/.github/workflows/phpunit-tests.yml
index 3fa1493605e45..53af817942511 100644
--- a/.github/workflows/phpunit-tests.yml
+++ b/.github/workflows/phpunit-tests.yml
@@ -46,7 +46,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest ]
-        php: [ '5.6', '7.0', '7.1', '7.2', '7.3', '7.4', '8.0', '8.1' ]
+        php: [ '5.6', '7.0', '7.4', '8.0', '8.1' ]
         db-type: [ 'mysql' ]
         db-version: [ '5.7' ]
         multisite: [ false, true ]
diff --git a/.github/workflows/slack-notifications.yml b/.github/workflows/slack-notifications.yml
deleted file mode 100644
index 4d646ac156df2..0000000000000
--- a/.github/workflows/slack-notifications.yml
+++ /dev/null
@@ -1,217 +0,0 @@
-##
-# A reusable workflow for posting messages to the Making WordPress
-# Core Slack Instance by submitting data to Slack webhook URLs
-# received by Slack Workflows.
-##
-name: Slack Notifications
-
-on:
-  workflow_run:
-    workflows:
-      - Code Coverage Report
-      - Coding Standards
-      - End-to-end Tests
-      - JavaScript Tests
-      - PHP Compatibility
-      - PHPUnit Tests
-      - Test NPM
-      - Test old branches
-    types:
-      - completed
-    branches:
-      - '[3-4].[0-9]'
-      - '5.[0-8]'
-
-  workflow_call:
-    inputs:
-      calling_status:
-        description: 'The status of the calling workflow'
-        type: string
-        required: true
-    secrets:
-      SLACK_GHA_SUCCESS_WEBHOOK:
-        description: 'The Slack webhook URL for a successful build.'
-        required: true
-      SLACK_GHA_CANCELLED_WEBHOOK:
-        description: 'The Slack webhook URL for a cancelled build.'
-        required: true
-      SLACK_GHA_FIXED_WEBHOOK:
-        description: 'The Slack webhook URL for a fixed build.'
-        required: true
-      SLACK_GHA_FAILURE_WEBHOOK:
-        description: 'The Slack webhook URL for a failed build.'
-        required: true
-
-env:
-  CURRENT_BRANCH: ${{ github.event_name == 'workflow_run' && github.event.workflow_run.head_branch || github.ref_name }}
-
-jobs:
-  # Gathers the details needed for Slack notifications.
-  #
-  # These details are passed as outputs to the subsequent, dependant jobs that
-  # submit data to Slack webhook URLs configured to post messages.
-  #
-  # Performs the following steps:
-  # - Retrieves the current workflow run.
-  # - Determine the conclusion of the previous workflow run or run attempt.
-  # - Sets the previous conclusion as an output.
-  # - Prepares the commit message.
-  # - Constructs and stores a message payload as an output.
-  prepare:
-    name: Prepare notifications
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event.workflow_run.event != 'pull_request' }}
-    outputs:
-      previous_conclusion: ${{ steps.previous-conclusion.outputs.previous_conclusion }}
-      payload: ${{ steps.create-payload.outputs.payload }}
-
-    steps:
-      - name: Determine the status of the previous attempt
-        id: previous-attempt-result
-        if: ${{ github.event_name == 'push' || github.event_name == 'schedule' || github.event_name == 'workflow_dispatch' }}
-        uses: actions/github-script@9ac08808f993958e9de277fe43a64532a609130e # v6.0.0
-        with:
-          script: |
-            const workflow_run = await github.rest.actions.getWorkflowRun({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              run_id: ${{ github.run_id }},
-            });
-
-            // When a workflow has been restarted to fix a failure, check the previous run attempt.
-            if ( workflow_run.data.run_attempt > 1 ) {
-              const previous_run = await github.rest.actions.getWorkflowRunAttempt({
-                owner: context.repo.owner,
-                repo: context.repo.repo,
-                run_id: ${{ github.run_id }},
-                attempt_number: workflow_run.data.run_attempt - 1
-              });
-
-              return previous_run.data.conclusion;
-            }
-
-            let workflow_id = '';
-            if ( ${{ github.event_name == 'workflow_run' }} ) {
-              workflow_id = '${{ github.event.workflow_run.workflow_id }}';
-            } else {
-              workflow_id = workflow_run.data.workflow_id;
-            }
-
-            // Otherwise, check the previous workflow run.
-            const previous_runs = await github.rest.actions.listWorkflowRuns({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              workflow_id: workflow_id,
-              branch: '${{ env.CURRENT_BRANCH }}',
-              exclude_pull_requests: true,
-            });
-
-            // This is the first workflow run for this branch or tag.
-            if ( previous_runs.data.workflow_runs.length == 0 ) {
-              return 'none';
-            }
-
-            // Find the workflow run for the commit that immediately preceded this one.
-            for ( let i = 0; i < previous_runs.data.workflow_runs.length; i++ ) {
-              if ( previous_runs.data.workflow_runs[ i ].run_number == workflow_run.data.run_number ) {
-                return previous_runs.data.workflow_runs[ i + 1 ].conclusion;
-              }
-            }
-
-            // Can't determine previous workflow conclusion.
-            return 'unknown';
-
-      - name: Store previous conclusion as an output
-        id: previous-conclusion
-        run: echo "::set-output name=previous_conclusion::${{ steps.previous-attempt-result.outputs.result }}"
-
-      - name: Get the commit message
-        id: current-commit-message
-        uses: actions/github-script@9ac08808f993958e9de277fe43a64532a609130e # v6.0.0
-        if: ${{ github.event_name == 'workflow_dispatch' || github.event_name == 'schedule' }}
-        with:
-          script: |
-            const commit_details = await github.rest.repos.getCommit({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              ref: '${{ github.sha }}'
-            });
-            return commit_details.data.commit.message;
-
-      - name: Prepare commit message.
-        id: commit-message
-        run: |
-          COMMIT_MESSAGE=$(cat <<'EOF' | awk 'NR==1' | sed 's/`/\\`/g' | sed 's/\"/\\\\\\"/g' | sed 's/\$/\\$/g'
-          ${{ github.event_name == 'workflow_run' && github.event.workflow_run.head_commit.message || ( github.event_name == 'workflow_dispatch' || github.event_name == 'schedule' ) && fromJson( steps.current-commit-message.outputs.result ) || github.event.head_commit.message }}
-          EOF
-          )
-          echo "::set-output name=commit_message_escaped::${COMMIT_MESSAGE}"
-
-      - name: Construct payload and store as an output
-        id: create-payload
-        run: echo "::set-output name=payload::{\"workflow_name\":\"${{ github.event_name == 'workflow_run' && github.event.workflow_run.name || github.workflow }}\",\"ref_name\":\"${{ env.CURRENT_BRANCH }}\",\"run_url\":\"https://github.com/WordPress/wordpress-develop/actions/runs/${{ github.event_name == 'workflow_run' && github.event.workflow_run.id || github.run_id }}\",\"commit_message\":\"${{ steps.commit-message.outputs.commit_message_escaped }}\"}"
-
-  # Posts notifications when a workflow fails.
-  failure:
-    name: Failure notifications
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    needs: [ prepare ]
-    if: ${{ github.event_name == 'workflow_run' && github.event.workflow_run.conclusion == 'failure' || inputs.calling_status == 'failure' || failure() }}
-
-    steps:
-      - name: Post failure notifications to Slack
-        uses: slackapi/slack-github-action@16b6c78ee73689a627b65332b34e5d409c7299da # v1.18.0
-        with:
-          payload: ${{ needs.prepare.outputs.payload }}
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
-
-  # Posts notifications the first time a workflow run succeeds after previously failing.
-  fixed:
-    name: Fixed notifications
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    needs: [ prepare ]
-    if: ${{ contains( fromJson( '["failure", "cancelled", "none"]' ), needs.prepare.outputs.previous_conclusion ) && ( github.event_name == 'workflow_run' && github.event.workflow_run.conclusion == 'success' || inputs.calling_status == 'success' ) && success() }}
-
-    steps:
-      - name: Post failure notifications to Slack
-        uses: slackapi/slack-github-action@16b6c78ee73689a627b65332b34e5d409c7299da # v1.18.0
-        with:
-          payload: ${{ needs.prepare.outputs.payload }}
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
-
-  # Posts notifications when a workflow is successful.
-  success:
-    name: Success notifications
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    needs: [ prepare ]
-    if: ${{ github.event_name == 'workflow_run' && github.event.workflow_run.conclusion == 'success' || inputs.calling_status == 'success' && success() }}
-
-    steps:
-      - name: Post success notifications to Slack
-        uses: slackapi/slack-github-action@16b6c78ee73689a627b65332b34e5d409c7299da # v1.18.0
-        with:
-          payload: ${{ needs.prepare.outputs.payload }}
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_GHA_SUCCESS_WEBHOOK }}
-
-  # Posts notifications when a workflow is cancelled.
-  cancelled:
-    name: Cancelled notifications
-    runs-on: ubuntu-latest
-    timeout-minutes: 5
-    needs: [ prepare ]
-    if: ${{ github.event_name == 'workflow_run' && github.event.workflow_run.conclusion == 'cancelled' || inputs.calling_status == 'cancelled' || cancelled() }}
-
-    steps:
-      - name: Post cancelled notifications to Slack
-        uses: slackapi/slack-github-action@16b6c78ee73689a627b65332b34e5d409c7299da # v1.18.0
-        with:
-          payload: ${{ needs.prepare.outputs.payload }}
-        env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
diff --git a/.github/workflows/test-coverage.yml b/.github/workflows/test-coverage.yml
deleted file mode 100644
index 9cb07627001bf..0000000000000
--- a/.github/workflows/test-coverage.yml
+++ /dev/null
@@ -1,213 +0,0 @@
-name: Code Coverage Report
-
-on:
-  # Verify
-  push:
-    branches:
-      - trunk
-    paths:
-      - '.github/workflows/test-coverage.yml'
-      - 'phpunit.xml.dist'
-      - 'tests/phpunit/multisite.xml'
-  # Once daily at 00:00 UTC.
-  schedule:
-    - cron: '0 0 * * *'
-  # Allow manually triggering the workflow.
-  workflow_dispatch:
-
-env:
-  PUPPETEER_SKIP_CHROMIUM_DOWNLOAD: ${{ true }}
-  LOCAL_PHP: '7.4-fpm'
-  LOCAL_PHP_XDEBUG: true
-  LOCAL_PHP_MEMCACHED: ${{ false }}
-
-jobs:
-  # Sets up WordPress for testing or development use.
-  #
-  # Performs the following steps:
-  # - Set environment variables.
-  # - Checks out the repository.
-  # - Checks out the WordPress Importer plugin (needed for the Core PHPUnit tests).
-  # - Logs debug information about the runner container.
-  # - Installs NodeJS 14.
-  # _ Installs NPM dependencies using install-changed to hash the `package.json` file.
-  # - Logs Docker debug information (about the Docker installation within the runner).
-  # - Starts the WordPress Docker container.
-  # - Logs debug general information.
-  # - Logs the running Docker containers.
-  # - Logs WordPress Docker container debug information.
-  # - Logs debug information about what's installed within the WordPress Docker containers.
-  # - Install WordPress within the Docker container.
-  # - Run the PHPUnit tests as a single site.
-  # - Ensures version-controlled files are not modified or deleted.
-  # - Upload the single site code coverage report to Codecov.io.
-  # - Run the PHPUnit tests as a multisite.
-  # - Ensures version-controlled files are not modified or deleted.
-  # - Upload the multisite code coverage report to Codecov.io.
-  test-coverage-report:
-    name: ${{ matrix.multisite && 'Multisite' || 'Single site' }} report
-    runs-on: ubuntu-latest
-    timeout-minutes: 120
-    if: ${{ github.repository == 'WordPress/wordpress-develop' }}
-    strategy:
-      fail-fast: false
-      matrix:
-        multisite: [ false, true ]
-
-    steps:
-      - name: Configure environment variables
-        run: |
-          echo "PHP_FPM_UID=$(id -u)" >> $GITHUB_ENV
-          echo "PHP_FPM_GID=$(id -g)" >> $GITHUB_ENV
-
-      - name: Checkout repository
-        uses: actions/checkout@ec3a7ce113134d7a93b817d10a8272cb61118579 # v2.4.0
-
-      - name: Log debug information
-        run: |
-          echo "$GITHUB_REF"
-          echo "$GITHUB_EVENT_NAME"
-          npm --version
-          node --version
-          curl --version
-          git --version
-          svn --version
-          php --version
-          php -i
-          locale -a
-
-      - name: Install NodeJS
-        uses: actions/setup-node@5b52f097d36d4b0b2f94ed6de710023fbb8b2236 # v3.1.0
-        with:
-          node-version-file: '.nvmrc'
-          cache: npm
-
-      - name: Install Dependencies
-        run: npm ci
-
-      # This date is used to ensure that the Composer cache is refreshed at least once every week.
-      # http://man7.org/linux/man-pages/man1/date.1.html
-      - name: "Get last Monday's date"
-        id: get-date
-        run: echo "date=$(/bin/date -u --date='last Mon' "+%F")" >> $GITHUB_OUTPUT
-
-      - name: Get Composer cache directory
-        id: composer-cache
-        run: echo "composer_dir=$(composer config cache-files-dir)" >> $GITHUB_OUTPUT
-
-      - name: Cache Composer dependencies
-        uses: actions/cache@136d96b4aee02b1f0de3ba493b1d47135042d9c0 # v3.0.1
-        env:
-          cache-name: cache-composer-dependencies
-        with:
-          path: ${{ steps.composer-cache.outputs.composer_dir }}
-          key: ${{ runner.os }}-php-${{ matrix.php }}-date-${{ steps.get-date.outputs.date }}-composer-${{ hashFiles('**/composer.json') }}
-
-      - name: Install Composer dependencies
-        run: |
-          docker-compose run --rm php composer --version
-
-          # Install using `composer update` as there is no `composer.lock` file.
-          docker-compose run --rm php composer update
-
-      - name: Docker debug information
-        run: |
-          docker -v
-          docker-compose -v
-
-      - name: Start Docker environment
-        run: |
-          npm run env:start
-
-      - name: General debug information
-        run: |
-          npm --version
-          node --version
-          curl --version
-          git --version
-          svn --version
-
-      - name: Log running Docker containers
-        run: docker ps -a
-
-      - name: WordPress Docker container debug information
-        run: |
-          docker-compose run --rm mysql mysql --version
-          docker-compose run --rm php php --version
-          docker-compose run --rm php php -m
-          docker-compose run --rm php php -i
-          docker-compose run --rm php locale -a
-
-      - name: Install WordPress
-        run: npm run env:install
-
-      - name: Run tests as a single site
-        if: ${{ ! matrix.multisite }}
-        run: npm run test:php -- --verbose -c phpunit.xml.dist --coverage-clover wp-code-coverage-single-clover-${{ github.sha }}.xml
-
-      - name: Ensure version-controlled files are not modified during the tests
-        run: git diff --exit-code
-
-      - name: Upload single site report to Codecov
-        if: ${{ ! matrix.multisite }}
-        uses: codecov/codecov-action@e3c560433a6cc60aec8812599b7844a7b4fa0d71 # v3.0.0
-        with:
-          file: wp-code-coverage-single-clover-${{ github.sha }}.xml
-          flags: single,php
-
-      - name: Run tests as a multisite install
-        if: ${{ matrix.multisite }}
-        run: npm run test:php -- --verbose -c tests/phpunit/multisite.xml --coverage-clover wp-code-coverage-multisite-clover-${{ github.sha }}.xml
-
-      - name: Ensure version-controlled files are not modified during the tests
-        run: git diff --exit-code
-
-      - name: Upload multisite report to Codecov
-        if: ${{ matrix.multisite }}
-        uses: codecov/codecov-action@f32b3a3741e1053eb607407145bc9619351dc93b # v2.1.0
-        with:
-          file: wp-code-coverage-multisite-clover-${{ github.sha }}.xml
-          flags: multisite,php
-
-  slack-notifications:
-    name: Slack Notifications
-    uses: WordPress/wordpress-develop/.github/workflows/slack-notifications.yml@trunk
-    needs: [ test-coverage-report ]
-    if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event_name != 'pull_request' && always() }}
-    with:
-      calling_status: ${{ needs.test-coverage-report.result == 'success' && 'success' || needs.test-coverage-report.result == 'cancelled' && 'cancelled' || 'failure' }}
-    secrets:
-      SLACK_GHA_SUCCESS_WEBHOOK: ${{ secrets.SLACK_GHA_SUCCESS_WEBHOOK }}
-      SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
-      SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
-      SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}
-
-  failed-workflow:
-    name: Failed workflow tasks
-    runs-on: ubuntu-latest
-    needs: [ test-coverage-report, slack-notifications ]
-    if: |
-      always() &&
-      github.repository == 'WordPress/wordpress-develop' &&
-      github.event_name != 'pull_request' &&
-      github.run_attempt < 2 &&
-      (
-        needs.test-coverage-report.result == 'cancelled' || needs.test-coverage-report.result == 'failure'
-      )
-
-    steps:
-      - name: Dispatch workflow run
-        uses: actions/github-script@d4560e157075e2d93aa3022b5b51a42a880f1f93 # v6.3.0
-        with:
-          retries: 2
-          retry-exempt-status-codes: 418
-          script: |
-            github.rest.actions.createWorkflowDispatch({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              workflow_id: 'failed-workflow.yml',
-              ref: 'trunk',
-              inputs: {
-                run_id: '${{ github.run_id }}'
-              }
-            });
diff --git a/.github/workflows/test-old-branches.yml b/.github/workflows/test-old-branches.yml
deleted file mode 100644
index 9626a4971df93..0000000000000
--- a/.github/workflows/test-old-branches.yml
+++ /dev/null
@@ -1,88 +0,0 @@
-name: Test old branches
-
-on:
-  # Verify the workflow is successful when this file is updated.
-  push:
-    branches:
-      - trunk
-    paths:
-      - '.github/workflows/test-old-branches.yml'
-  # Run twice a month on the 1st and 15th at 00:00 UTC.
-  schedule:
-    - cron: '0 0 1 * *'
-    - cron: '0 0 15 * *'
-
-jobs:
-  dispatch-workflows-for-old-branches:
-    name: ${{ matrix.workflow }} for ${{ matrix.branch }}
-    runs-on: ubuntu-latest
-    timeout-minutes: 20
-    if: ${{ github.repository == 'WordPress/wordpress-develop' }}
-    strategy:
-      fail-fast: false
-      matrix:
-        workflow: [
-            'coding-standards.yml',
-            'javascript-tests.yml',
-            'phpunit-tests.yml',
-            'test-npm.yml'
-        ]
-        branch: [
-            '5.9', '5.8', '5.7', '5.6', '5.5', '5.4', '5.3', '5.2', '5.1', '5.0',
-            '4.9', '4.8', '4.7', '4.6', '4.5', '4.4', '4.3', '4.2', '4.1', '4.0',
-            '3.9', '3.8', '3.7'
-        ]
-        include:
-          # PHP Compatibility testing was introduced in 5.5.
-          - branch: '5.9'
-            workflow: 'php-compatibility.yml'
-          - branch: '5.8'
-            workflow: 'php-compatibility.yml'
-          - branch: '5.7'
-            workflow: 'php-compatibility.yml'
-          - branch: '5.6'
-            workflow: 'php-compatibility.yml'
-          - branch: '5.5'
-            workflow: 'php-compatibility.yml'
-
-          # End-to-end testing was introduced in 5.3 but was later removed as there were no meaningful assertions.
-          # Starting in 5.8 with #52905, some additional tests with real assertions were introduced.
-          # Branches 5.8 and newer should be tested to confirm no regressions are introduced.
-          - branch: '5.9'
-            workflow: 'end-to-end-tests.yml'
-          - branch: '5.8'
-            workflow: 'end-to-end-tests.yml'
-        exclude:
-          # Coding standards and JavaScript testing did not take place in 3.7.
-          - branch: '3.7'
-            workflow: 'coding-standards.yml'
-          - branch: '3.7'
-            workflow: 'javascript-tests.yml'
-
-    # Run all branches monthly, but only the currently supported one twice per month.
-    steps:
-      - name: Dispatch workflow run
-        uses: actions/github-script@9ac08808f993958e9de277fe43a64532a609130e # v6.0.0
-        if: ${{ github.event_name == 'push' || github.event.schedule == '0 0 15 * *' || matrix.branch == '5.9' }}
-        with:
-          github-token: ${{ secrets.GHA_OLD_BRANCH_DISPATCH }}
-          script: |
-            github.rest.actions.createWorkflowDispatch({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              workflow_id: '${{ matrix.workflow }}',
-              ref: '${{ matrix.branch }}'
-            });
-
-  slack-notifications:
-    name: Slack Notifications
-    uses: WordPress/wordpress-develop/.github/workflows/slack-notifications.yml@trunk
-    needs: [ dispatch-workflows-for-old-branches ]
-    if: ${{ github.repository == 'WordPress/wordpress-develop' && github.event_name != 'pull_request' && always() }}
-    with:
-      calling_status: ${{ needs.dispatch-workflows-for-old-branches.result == 'success' && 'success' || needs.dispatch-workflows-for-old-branches.result == 'cancelled' && 'cancelled' || 'failure' }}
-    secrets:
-      SLACK_GHA_SUCCESS_WEBHOOK: ${{ secrets.SLACK_GHA_SUCCESS_WEBHOOK }}
-      SLACK_GHA_CANCELLED_WEBHOOK: ${{ secrets.SLACK_GHA_CANCELLED_WEBHOOK }}
-      SLACK_GHA_FIXED_WEBHOOK: ${{ secrets.SLACK_GHA_FIXED_WEBHOOK }}
-      SLACK_GHA_FAILURE_WEBHOOK: ${{ secrets.SLACK_GHA_FAILURE_WEBHOOK }}