*: add grpc rate limit tests

[rleungx]

What problem does this PR solve?

Issue Number: ref #7167, ref #5739

What is changed and how does it work?

Check List

Tests

• Unit test

Release note

None.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.61%. Comparing base (23d544f) to head (1e8a328).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #8635      +/-   ##
==========================================
+ Coverage   77.54%   77.61%   +0.07%     
==========================================
  Files         474      474              
  Lines       61940    62097     +157     
==========================================
+ Hits        48032    48198     +166     
+ Misses      10355    10346       -9     
  Partials     3553     3553              

Flag	Coverage Δ
unittests	77.61% <100.00%> (+0.07%)	⬆️

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lhy1024, nolouch

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• OWNERS [lhy1024,nolouch]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-09-20 09:43:32.82520119 +0000 UTC m=+1213482.565625151: ☑️ agreed by nolouch.
• 2024-09-23 02:43:29.862917013 +0000 UTC m=+1447479.603340936: ☑️ agreed by lhy1024.