chore: clean up unused API code after moving to v1beta1

[odubajDT]

This PR

• removes conversion and and validation webhook logic
• removes struct functions of v1alpha* API definitions
• removes unused tests
• enables api unit tests to be executed with the operator unit tests

Related Issues

Fixes #532

Depends on: #539

[codecov]

Codecov Report

Merging #543 (be8bac3) into main (d234410) will increase coverage by 2.37%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #543      +/-   ##
==========================================
+ Coverage   81.86%   84.23%   +2.37%     
==========================================
  Files           7       10       +3     
  Lines         805     1015     +210     
==========================================
+ Hits          659      855     +196     
- Misses        118      130      +12     
- Partials       28       30       +2     

see 3 files with indirect coverage changes

Flag	Coverage Δ
unit-tests	84.23% <ø> (+2.37%)	⬆️

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