Ensure stream closed

[aphralG]

Proposed changes

This PR fixes the file upload logic in FileServiceOperator to ensure that when sending files over 1MB (using chunked streaming), the agent closes the gRPC stream and waits for the NGINX One Console response only after all file chunks have been sent.

Details

Previously, the stream might not have been properly closed after sending all chunks, potentially causing incomplete uploads or missing server responses.
Now, after all chunks are sent in sendFileUpdateStreamChunks, the agent calls CloseAndRecv() on the stream client, ensuring the stream is closed and the server response is received before proceeding.

Impact

• Ensures reliable file uploads for large files.
• Prevents issues with incomplete or unacknowledged uploads.

Copy of #1522 due to issue with PR

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

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.02%. Comparing base (48f97f4) to head (7017443).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1527   +/-   ##
=======================================
  Coverage   85.02%   85.02%           
=======================================
  Files         103      103           
  Lines       13587    13588    +1     
=======================================
+ Hits        11552    11553    +1     
  Misses       1518     1518           
  Partials      517      517           

Files with missing lines	Coverage Δ
internal/file/file_service_operator.go	77.53% <100.00%> (+0.06%)	⬆️

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