Limit the number of concurrent gRPC requests (#27718)

[yah01]

/kind improvement
pr: #27718

[sre-ci-robot]

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[mergify]

@yah01 E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[codecov]

Codecov Report

Merging #27719 (1b20c6a) into 2.2.0 (6fee34f) will increase coverage by 0.01%.
Report is 3 commits behind head on 2.2.0.
The diff coverage is 85.00%.

@@            Coverage Diff             @@
##            2.2.0   #27719      +/-   ##
==========================================
+ Coverage   80.93%   80.94%   +0.01%     
==========================================
  Files         745      745              
  Lines      109239   109269      +30     
==========================================
+ Hits        88408    88451      +43     
+ Misses      17474    17465       -9     
+ Partials     3357     3353       -4     

Files	Coverage Δ
internal/distributed/datacoord/service.go	86.41% <100.00%> (+0.05%)	⬆️
internal/distributed/datanode/service.go	76.54% <100.00%> (+0.09%)	⬆️
internal/distributed/indexnode/service.go	68.96% <100.00%> (+0.17%)	⬆️
internal/distributed/proxy/service.go	75.23% <100.00%> (+0.06%)	⬆️
internal/distributed/querycoord/service.go	71.82% <100.00%> (+0.11%)	⬆️
internal/distributed/querynode/service.go	81.59% <100.00%> (+0.09%)	⬆️
internal/distributed/rootcoord/service.go	80.00% <100.00%> (+0.07%)	⬆️
internal/util/paramtable/grpc_param.go	78.72% <75.00%> (-0.17%)	⬇️

... and 21 files with indirect coverage changes

[congqixia]

the parameter this pr set is MaxConcurrentStreams, which is not equivalent to concurrent requests

[yah01]

/hold