Add ADR explaining removal of kubebuilder defaults

[alexander-demicev]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged): Fixes #

Special notes for your reviewer:

Checklist:

• [ ] squashed commits into logical changes
• [ ] includes documentation
• [ ] adds unit tests
• [ ] adds or updates e2e tests

[Danil-Grigorev]

@salasberryfin Defaults are only evaluated on the first apply, then the applied data is stored in etcd, so all existing manifests should already have user defined values for these fields.

[salasberryfin]

Thanks @Danil-Grigorev.