syncer: exit watch leader immediately

[rleungx]

What problem does this PR solve?

Issue Number: Close #8823

What is changed and how does it work?

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: JmPotato, nolouch

The full list of commands accepted by this bot can be found here.

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Needs approval from an approver in each of these files:

• OWNERS [JmPotato,nolouch]

Approvers can indicate their approval by writing /approve in a comment
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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-19 08:11:01.688969268 +0000 UTC m=+948623.879838249: ☑️ agreed by JmPotato.
• 2024-11-19 08:50:57.572533724 +0000 UTC m=+951019.763402721: ☑️ agreed by nolouch.

[JmPotato]

/retest

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.26%. Comparing base (76e3b43) to head (0e396cf).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8824      +/-   ##
==========================================
+ Coverage   75.24%   75.26%   +0.01%     
==========================================
  Files         456      456              
  Lines       71608    71616       +8     
==========================================
+ Hits        53884    53902      +18     
+ Misses      14295    14278      -17     
- Partials     3429     3436       +7     

Flag	Coverage Δ
unittests	75.26% <100.00%> (+0.01%)	⬆️

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

---- 🚨 Try these New Features:

• Flaky Tests Detection - Detect and resolve failed and flaky tests

[rleungx]

/hold

[rleungx]

/hold cancel

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.5: #8827.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.1: #8828.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #8829.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #8830.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #8831.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-5.4: #8832.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-6.1: #8834.