enhance: remove the rpc level of coordinator

[chyezh]

issue: #33285
pr: #37722

• move most cgo opeartions related to search/query into segcore package for reusing for streamingnode.
• add go unittest for segcore operations.

[sre-ci-robot]

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[codecov]

Codecov Report

Attention: Patch coverage is 96.83210% with 30 lines in your changes missing coverage. Please review.

Project coverage is 80.73%. Comparing base (0bd2617) to head (18485f0).
Report is 7 commits behind head on 10kcp.

Files with missing lines	Patch %	Lines
internal/coordinator/coordclient/rootcoord.go	92.68%	24 Missing ⚠️
internal/coordinator/coordclient/registry.go	88.88%	3 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            10kcp   #37876      +/-   ##
==========================================
+ Coverage   80.63%   80.73%   +0.10%     
==========================================
  Files        1069     1074       +5     
  Lines      166978   167906     +928     
==========================================
+ Hits       134643   135560     +917     
- Misses      27930    27949      +19     
+ Partials     4405     4397       -8     

Files with missing lines	Coverage Δ
internal/coordinator/coordclient/datacoord.go	100.00% <100.00%> (ø)
internal/coordinator/coordclient/querycoord.go	100.00% <100.00%> (ø)
internal/datacoord/server.go	72.52% <100.00%> (ø)
internal/distributed/datacoord/service.go	88.21% <100.00%> (+0.04%)	⬆️
internal/distributed/querycoord/service.go	79.02% <100.00%> (+1.98%)	⬆️
internal/distributed/rootcoord/service.go	81.08% <100.00%> (+0.88%)	⬆️
pkg/util/syncutil/future.go	100.00% <100.00%> (ø)
internal/coordinator/coordclient/registry.go	88.88% <88.88%> (ø)
internal/coordinator/coordclient/rootcoord.go	92.68% <92.68%> (ø)

... and 36 files with indirect coverage changes

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