Fix connection reset logic to ensure the old subscribe goroutine is cancelled before a new connection is made

[dhurley]

Proposed changes

• A gRPC server that is tracking connections could remove a connection when the Subscribe stream is closed by the client and then track a connection again if it receives a CreateConnection RPC call. So we need to ensure that the old subscribe goroutine is cancelled before a new connection is made when a connection reset happens to ensure that the server is able to track connections.
• Also I spotted a potential race condition in file service operator so I provided a fix for that as well.
• Updated ValidateGrpcError function to return permanent error for NotFound, AlreadyExists, PermissionDenied or Unauthenticated gRPC errors.

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING document
• I have run make install-tools and have attached any dependency changes to this pull request
• If applicable, I have added tests that prove my fix is effective or that my feature works
• If applicable, I have checked that any relevant tests pass after adding my changes
• If applicable, I have updated any relevant documentation (README.md)
• If applicable, I have tested my cross-platform changes on Ubuntu 22, Redhat 8, SUSE 15 and FreeBSD 13

[codecov]

Codecov Report

❌ Patch coverage is 76.19048% with 10 lines in your changes missing coverage. Please review.
✅ Project coverage is 84.99%. Comparing base (721944d) to head (5f9e2e3).
⚠️ Report is 48 commits behind head on main.

Files with missing lines	Patch %	Lines
internal/file/file_service_operator.go	72.72%	2 Missing and 4 partials ⚠️
internal/command/command_plugin.go	76.47%	3 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1700      +/-   ##
==========================================
- Coverage   85.00%   84.99%   -0.01%     
==========================================
  Files         105      105              
  Lines       13593    13625      +32     
==========================================
+ Hits        11555    11581      +26     
- Misses       1524     1527       +3     
- Partials      514      517       +3     

Files with missing lines	Coverage Δ
internal/grpc/grpc.go	81.57% <100.00%> (+0.16%)	⬆️
internal/command/command_plugin.go	71.60% <76.47%> (+0.79%)	⬆️
internal/file/file_service_operator.go	77.81% <72.72%> (+0.27%)	⬆️

... and 7 files with indirect coverage changes

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