enhance: [2.4] Refine Replica manager colle2Replicas secondary index (#37906)

[congqixia]

Cherry-pick from master
pr: #37906
Related to #37630

This PR add a new util coll2Replicas secondary index to reduce map access & iteration while get replicas by collection

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[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[codecov]

Codecov Report

Attention: Patch coverage is 90.47619% with 4 lines in your changes missing coverage. Please review.

Project coverage is 80.63%. Comparing base (4aca68a) to head (5bee7e5).
Report is 10 commits behind head on 2.4.

Files with missing lines	Patch %	Lines
internal/querycoordv2/meta/replica_manager.go	90.47%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.4   #37970      +/-   ##
==========================================
+ Coverage   72.24%   80.63%   +8.38%     
==========================================
  Files        1069     1069              
  Lines      166979   166986       +7     
==========================================
+ Hits       120641   134653   +14012     
+ Misses      41919    27927   -13992     
+ Partials     4419     4406      -13     

Files with missing lines	Coverage Δ
internal/querycoordv2/meta/replica_manager.go	82.20% <90.47%> (+0.39%)	⬆️

... and 233 files with indirect coverage changes

[weiliu1031]

/lgtm