chore: TransactionPoller cleanup

[jpuri]

Explanation

Small transaction poller cleanup PR. Discussion here: #7822 (comment)

References

• Related to https://github.com/MetaMask/MetaMask-planning/issues/6948

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Medium Risk
Changes when websocket-driven polling is triggered, which could increase polling or cause unintended refreshes if unrelated transaction update events match pending hashes.

Overview
TransactionPoller no longer filters AccountActivityService:transactionUpdated events by chain ID (CAIP-2 conversion) or by the selected account address; it now triggers a poll for any confirmed/dropped/failed event whose transaction.id matches a pending transaction hash.

Tests were updated to reflect the relaxed filtering (simpler messenger mock, removed non-matching chain/account cases, and adjusted expectations/descriptions).

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[jpuri]

Since we are checking for pending transactions, other check are redundant.