Add automated tests for -watch-secret-namespace

[vepatel]

Proposed changes

• Add 5 tests for diff. -watch-secret-namespace scenarios
• Add helper function to check connection with specific SNI

Checklist

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

• 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

[codecov-commenter]

Codecov Report

Merging #3245 (90d672d) into main (c676edb) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #3245      +/-   ##
==========================================
- Coverage   52.67%   52.64%   -0.03%     
==========================================
  Files          59       59              
  Lines       16107    16107              
==========================================
- Hits         8484     8480       -4     
- Misses       7341     7343       +2     
- Partials      282      284       +2     

Impacted Files	Coverage Δ
internal/k8s/configuration.go	95.39% <0.00%> (-0.37%)	⬇️

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