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:

• HuSharp
• bufferflies

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[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: -0.14 ⚠️

Comparison is base (8c09be1) 75.61% compared to head (aeb42df) 75.48%.

❗ Current head aeb42df differs from pull request most recent head 0275cba. Consider uploading reports for the commit 0275cba to get more accurate results

Additional details and impacted files

@@               Coverage Diff               @@
##           release-6.1    #6701      +/-   ##
===============================================
- Coverage        75.61%   75.48%   -0.14%     
===============================================
  Files              307      307              
  Lines            30502    30506       +4     
===============================================
- Hits             23065    23027      -38     
- Misses            5447     5475      +28     
- Partials          1990     2004      +14     

Flag	Coverage Δ
unittests	75.48% <100.00%> (-0.14%)	⬇️

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

Impacted Files	Coverage Δ
server/election/leadership.go	74.25% <100.00%> (-4.10%)	⬇️

... and 24 files with indirect coverage changes

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[lhy1024]

/merge

[ti-chi-bot]

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[ti-chi-bot]

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

Commit hash: 0275cba