Fix HPA race condition by reading deployment replicas instead of HPA …

[ciarams87]

…status (#4214)

When HPA is enabled, read the current Deployment.Spec.Replicas directly instead of HPA.Status.DesiredReplicas, which is eventually consistent and lags behind deployment changes. This prevents the controller from overwriting HPA's replica count with stale values, eliminating pod churn and connection drops.

Fixes race condition where HPA scales down → NGF reads stale HPA status → NGF overwrites deployment with old replica count → pods restart.

Cherry-pick of #4214

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

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

Preserve HPA replicas on deployment

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.10%. Comparing base (bd30d48) to head (98f3b33).
⚠️ Report is 1 commits behind head on release-2.2.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-2.2    #4239      +/-   ##
===============================================
- Coverage        86.13%   86.10%   -0.03%     
===============================================
  Files              131      131              
  Lines            14248    14257       +9     
  Branches            74       74              
===============================================
+ Hits             12272    12276       +4     
- Misses            1774     1778       +4     
- Partials           202      203       +1     

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[sjberman]

Be sure for future cherry pick PRs that the branch uses the proper name (bug/, fix/`, etc) so that the PR gets the proper labels for the auto-generated release notes.