test: improve gRPC unit tests stability

[DMwangnima]

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test

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 60.50%. Comparing base (fefa17d) to head (49fad62).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1800      +/-   ##
==========================================
+ Coverage   60.41%   60.50%   +0.09%     
==========================================
  Files         381      381              
  Lines       34515    34515              
==========================================
+ Hits        20851    20883      +32     
+ Misses      12387    12363      -24     
+ Partials     1277     1269       -8     

Flag	Coverage Δ
integration	48.55% <ø> (+0.20%)	⬆️
unit	50.87% <ø> (+0.01%)	⬆️

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