Run some unit tests in parallel

[henrymercer]

Drop the --serial flag we pass to ava in favour of specifying which tests need to be run sequentially. These are typically ones which read and write environment variables. This speeds up the unit tests by 4x on my machine from ~24s to ~6s (measured fairly unscientifically by comparing 5 runs of each).

[Copilot]

Pull request overview

This PR updates the AVA test configuration to allow parallel test execution, while explicitly marking tests that rely on shared mutable state (notably process.env) as sequential to preserve correctness.

Changes:

• Remove the global --serial flag from the ava npm script to enable parallel test runs.
• Convert many unit tests to test.serial(...) where they mutate environment variables or other shared state.
• Regenerate corresponding compiled lib/* JavaScript artifacts to reflect package.json changes.

Reviewed changes

Copilot reviewed 39 out of 39 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/workflow.test.ts	Marks env-dependent workflow validation tests as serial.
src/util.test.ts	Marks env-mutating util tests as serial (extra options, env var helpers, etc.).
src/upload-sarif.test.ts	Marks SARIF upload macro tests and tmp-dir tests as serial.
src/trap-caching.test.ts	Marks cache-related tests that touch env/event files as serial.
src/status-report.test.ts	Marks status-report tests as serial to avoid env interference.
src/start-proxy/environment.test.ts	Marks proxy environment tests as serial due to env mutations.
src/start-proxy.test.ts	Marks start-proxy tests as serial (credentials/env/error-message behavior).
src/setup-codeql.test.ts	Marks setup-codeql tests as serial (platform/env/toolcache stubbing).
src/overlay/status.test.ts	Marks overlay cache status tests as serial (RUNNER_TEMP/cache stubbing).
src/overlay/index.test.ts	Marks overlay change-file/cache-key tests as serial.
src/init.test.ts	Marks tests that rely on shared env/stubs as serial.
src/init-action-post-helper.test.ts	Marks init-post tests as serial (env-driven execution paths).
src/git-utils.test.ts	Marks git-utils tests as serial (env + global stubbing of git helpers).
src/feature-flags/properties.test.ts	Marks repository properties feature-flag tests as serial.
src/feature-flags.test.ts	Marks feature flag tests as serial to avoid shared env/cache interference.
src/diff-informed-analysis-utils.test.ts	Marks diff-informed analysis tests as serial.
src/dependency-caching.test.ts	Marks dependency-caching tests as serial where env/stubs are involved.
src/database-upload.test.ts	Marks database upload tests as serial (env + HTTP mocking).
src/cli-errors.test.ts	Marks platform/arch stubbing tests as serial.
src/api-client.test.ts	Marks API-client tests as serial.
src/analyze.test.ts	Marks analyze status report test as serial.
src/analyses.test.ts	Marks analysis-kinds and risk assessment tests as serial.
src/actions-util.test.ts	Marks some actions-util tests as serial; further serialisation may be needed for github.context mutation.
package.json	Removes ava --serial to allow parallel execution.
lib/upload-sarif-action.js	Compiled output update (generated from TS / package changes).
lib/upload-sarif-action-post.js	Compiled output update (generated).
lib/upload-lib.js	Compiled output update (generated).
lib/start-proxy-action.js	Compiled output update (generated).
lib/start-proxy-action-post.js	Compiled output update (generated).
lib/setup-codeql-action.js	Compiled output update (generated).
lib/resolve-environment-action.js	Compiled output update (generated).
lib/init-action.js	Compiled output update (generated).
lib/init-action-post.js	Compiled output update (generated).
lib/autobuild-action.js	Compiled output update (generated).
lib/analyze-action.js	Compiled output update (generated).
lib/analyze-action-post.js	Compiled output update (generated).