chore(gRPC): deprecate gRPC GetServerConn

[DMwangnima]

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chore

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新版的 unknown handler 可以完全取代旧版的 grpcproxy，正式废弃GetServerConn

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.92%. Comparing base (bfa27f3) to head (2b8b2e2).
⚠️ Report is 48 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1955      +/-   ##
==========================================
+ Coverage   61.37%   62.92%   +1.54%     
==========================================
  Files         388      394       +6     
  Lines       35063    30267    -4796     
==========================================
- Hits        21521    19046    -2475     
+ Misses      12247     9931    -2316     
+ Partials     1295     1290       -5     

Flag	Coverage Δ
integration	51.87% <ø> (+1.36%)	⬆️
unit	53.46% <ø> (+1.81%)	⬆️

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