enhance: [2.4] Support proxy/delegator qn client pooling

[congqixia]

Cherry pick from master
pr: #35194
See also #35196
Add param item for proxy/delegator query node client pooling and implement pooling logic

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• configs/OWNERS [congqixia]
• internal/proxy/OWNERS [congqixia]
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[codecov]

Codecov Report

Attention: Patch coverage is 86.58537% with 11 lines in your changes missing coverage. Please review.

Project coverage is 72.18%. Comparing base (f718410) to head (6480cf4).
Report is 3 commits behind head on 2.4.

Files	Patch %	Lines
internal/querynodev2/cluster/worker.go	82.92%	4 Missing and 3 partials ⚠️
internal/proxy/shard_client.go	83.33%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #35195      +/-   ##
==========================================
- Coverage   81.13%   72.18%   -8.95%     
==========================================
  Files        1052     1052              
  Lines      136740   136806      +66     
==========================================
- Hits       110942    98752   -12190     
- Misses      21586    33867   +12281     
+ Partials     4212     4187      -25     

Files	Coverage Δ
internal/querynodev2/server.go	76.78% <100.00%> (+0.62%)	⬆️
pkg/util/paramtable/component_param.go	98.55% <100.00%> (+<0.01%)	⬆️
internal/proxy/shard_client.go	80.30% <83.33%> (-10.61%)	⬇️
internal/querynodev2/cluster/worker.go	85.71% <82.92%> (-3.48%)	⬇️

... and 236 files with indirect coverage changes

[weiliu1031]

/lgtm