leadership: avoid potential data race (#6636)

[ti-chi-bot]

This is an automated cherry-pick of #6636

What problem does this PR solve?

Issue Number: Close #6635

What is changed and how does it work?

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• JmPotato
• rleungx

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[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by release team.
Adding the do-not-merge/cherry-pick-not-approved label.

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[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.12 🎉

Comparison is base (0934e64) 74.52% compared to head (d271302) 74.64%.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-7.2    #6639      +/-   ##
===============================================
+ Coverage        74.52%   74.64%   +0.12%     
===============================================
  Files              417      417              
  Lines            43056    43060       +4     
===============================================
+ Hits             32086    32143      +57     
+ Misses            8113     8073      -40     
+ Partials          2857     2844      -13     

Flag	Coverage Δ
unittests	74.64% <100.00%> (+0.12%)	⬆️

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

Impacted Files	Coverage Δ
pkg/election/leadership.go	85.14% <100.00%> (-0.42%)	⬇️

... and 27 files with indirect coverage changes

☔ View full report in Codecov by Sentry.
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[JmPotato]

/merge

[ti-chi-bot]

@JmPotato: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: d271302

[lhy1024]

7.2 is code freeze and only is allowed to pick block issues.