RTC: Backport race condition fix

[chriszarate]

What?

Backport race condition fix from WordPress/wordpress-develop#11292

IMPORTANT: This should only be merged if we do not proceed with the custom table approach.

Why?

A race condition exists when applying compaction updates using the default polling provider.

[github-actions]

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Co-authored-by: alecgeatches <alecgeatches@git.wordpress.org>
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[github-actions]

Flaky tests detected in f91d8e6.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/23265816185
📝 Reported issues:

• [Flaky Test] Should render and migrate legacy openSubmenusOnClick blocks #75559 in /test/e2e/specs/editor/blocks/navigation-frontend-interactivity.spec.js
• [Flaky Test] post title and content are editable and blocks can be inserted #76524 in /test/e2e/specs/editor/various/post-content-focus-mode.spec.js

[alecgeatches]

The meta_id-based logic looks correct, and in my local testing I didn't see any odd behavior during compaction. Any interest in moving the tests from WordPress/wordpress-develop#11292 over here?

[chriszarate]

Any interest in moving the tests from WordPress/wordpress-develop#11292 over here?

Looks like we're inconsistent in doing so. It's a good suggestion, but might tackle post-RC1 since there could be conflicts with other work.