*: make TestRateLimitConfigReload stable

[rleungx]

What problem does this PR solve?

Issue Number: Close #8083.

What is changed and how does it work?

MustWaitLeader may return nil before because it only tries to iterate servers once.

Check List

Tests

• Unit test

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• lhy1024

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[rleungx]

/hold

[codecov]

Codecov Report

Merging #8092 (2e7f503) into master (956684a) will decrease coverage by 0.02%.
Report is 2 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head 2e7f503 differs from pull request most recent head 123688c. Consider uploading reports for the commit 123688c to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8092      +/-   ##
==========================================
- Coverage   77.31%   77.30%   -0.02%     
==========================================
  Files         470      470              
  Lines       61115    61129      +14     
==========================================
+ Hits        47252    47255       +3     
- Misses      10298    10308      +10     
- Partials     3565     3566       +1     

Flag	Coverage Δ
unittests	77.30% <100.00%> (-0.02%)	⬇️

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[rleungx]

/hold cancel

[rleungx]

/merge

[ti-chi-bot]

@rleungx: 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: 9b8b334

[rleungx]

/merge

[ti-chi-bot]

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

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

If you have any questions about the PR merge process, please refer to pr process.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

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

Commit hash: 123688c