Fix empty pod owner name when connecting to agent

[sjberman]

Problem: Saw an issue where nginx failed to connect to the control plane due to an empty hostname and not being able to find the pod name.

Solution: If ContainerInfo provided by agent is empty, fall back to HostInfo. This should cover all bases to ensure we get the hostname.

Testing: Fixed my issue that I saw locally.

Closes #4366

Checklist

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• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

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please add a brief note that summarizes the change.

Fixed an issue where control plane and data plane failed to connect due to empty pod name (hostname).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.08%. Comparing base (2a64f38) to head (a26a62d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4367      +/-   ##
==========================================
- Coverage   86.08%   86.08%   -0.01%     
==========================================
  Files         132      132              
  Lines       14342    14344       +2     
  Branches       35       35              
==========================================
+ Hits        12347    12348       +1     
- Misses       1791     1792       +1     
  Partials      204      204              

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