chore: refactor admission webhook tests

[odubajDT]

This PR

• migrate webhook ginkgo tests to standard unit tests
• minor refactoring of admission webhook

[skyerus]

Table tests ftw :)

[codecov]

Codecov Report

Merging #409 (7d0bfa4) into main (3212eba) will decrease coverage by 1.64%.
The diff coverage is 86.36%.

@@            Coverage Diff             @@
##             main     #409      +/-   ##
==========================================
- Coverage   72.72%   71.09%   -1.64%     
==========================================
  Files          11       11              
  Lines         847      851       +4     
==========================================
- Hits          616      605      -11     
- Misses        205      217      +12     
- Partials       26       29       +3     

Impacted Files	Coverage Δ
webhooks/featureflagconfiguration_webhook.go	81.25% <86.36%> (-5.12%)	⬇️

... and 1 file with indirect coverage changes

Flag	Coverage Δ
component-tests	64.80% <86.36%> (-2.07%)	⬇️
unit-tests	24.55% <86.36%> (+3.78%)	⬆️

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