gc(ticdc): fix data race in gc manager

[sdojjy]

What problem does this PR solve?

Issue Number: close #10688
fix data race

What is changed and how it works?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

`None`.

[codecov]

Codecov Report

Merging #10846 (cc1804e) into master (99b3eb4) will increase coverage by 3.6334%.
Report is 9 commits behind head on master.
The diff coverage is 100.0000%.

Additional details and impacted files

Components	Coverage Δ
cdc	61.9096% <100.0000%> (∅)
dm	51.2131% <ø> (-0.0061%)	⬇️
engine	63.3879% <ø> (+0.0155%)	⬆️

Flag	Coverage Δ
unit	57.5553% <100.0000%> (+3.6334%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master     #10846        +/-   ##
================================================
+ Coverage   53.9219%   57.5553%   +3.6334%     
================================================
  Files           403        853       +450     
  Lines         63655     126937     +63282     
================================================
+ Hits          34324      73059     +38735     
- Misses        26627      48440     +21813     
- Partials       2704       5438      +2734     

[sdojjy]

/retest-required

[sdojjy]

/retest-required

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3AceShowHand, asddongmen

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-03-26 02:32:04.203447416 +0000 UTC m=+1948751.225693805: ☑️ agreed by asddongmen.
• 2024-03-26 02:33:54.475611872 +0000 UTC m=+1948861.497858260: ☑️ agreed by 3AceShowHand.

[3AceShowHand]

This is cherry-pick back to release-7.5 by the PR #10646

[ti-chi-bot]

In response to a cherrypick label: new pull request could not be created: failed to create pull request against pingcap/tiflow#release-7.5 from head ti-chi-bot:cherry-pick-10846-to-release-7.5: status code 422 not one of [201], body: {"message":"Validation Failed","errors":[{"resource":"PullRequest","code":"custom","message":"No commits between pingcap:release-7.5 and ti-chi-bot:cherry-pick-10846-to-release-7.5"}],"documentation_url":"https://docs.github.com/rest/pulls/pulls#create-a-pull-request"}