Replace deprecated grpc WithInsecure option

[congqixia]

/kind improvement

[sre-ci-robot]

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[jiaoew1991]

/lgtm

[codecov]

Codecov Report

Merging #26226 (c26e457) into master (21eeb37) will decrease coverage by 0.01%.
Report is 6 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #26226      +/-   ##
==========================================
- Coverage   82.58%   82.57%   -0.01%     
==========================================
  Files         811      811              
  Lines      108725   108753      +28     
==========================================
+ Hits        89790    89807      +17     
- Misses      15805    15818      +13     
+ Partials     3130     3128       -2     

Files Changed	Coverage Δ
internal/distributed/connection_manager.go	70.41% <100.00%> (+0.33%)	⬆️
internal/util/grpcclient/client.go	79.60% <100.00%> (-0.96%)	⬇️

... and 21 files with indirect coverage changes