[fix][test] Fixed too short wait in ResourceGroupRateLimiterTest

[merlimat]

Fixes #20385

Motivation

The test wait time is too short.

Verifying this change

• Make sure that the change passes the CI checks.

(Please pick either of the following options)

This change is a trivial rework / code cleanup without any test coverage.

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This change is already covered by existing tests, such as (please describe tests).

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This change added tests and can be verified as follows:

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• Added integration tests for end-to-end deployment with large payloads (10MB)
• Extended integration test for recovery after broker failure

Does this pull request potentially affect one of the following parts:

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• Dependencies (add or upgrade a dependency)
• The public API
• The schema
• The default values of configurations
• The threading model
• The binary protocol
• The REST endpoints
• The admin CLI options
• The metrics
• Anything that affects deployment

Documentation

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Matching PR in forked repository

PR in forked repository:

[codecov-commenter]

Codecov Report

Merging #21509 (01919db) into master (78fc853) will increase coverage by 39.87%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master   #21509       +/-   ##
=============================================
+ Coverage     33.39%   73.27%   +39.87%     
- Complexity    12194    32612    +20418     
=============================================
  Files          1638     1890      +252     
  Lines        127949   140440    +12491     
  Branches      13952    15436     +1484     
=============================================
+ Hits          42733   102901    +60168     
+ Misses        79564    29454    -50110     
- Partials       5652     8085     +2433     

Flag	Coverage Δ
inttests	24.19% <ø> (+0.04%)	⬆️
systests	24.78% <ø> (?)
unittests	72.54% <ø> (+40.72%)	⬆️

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