Cleanup: remove kubebuilder-generated files that were never updated.

Kubebuilder was used to originally generate the CRDs, but for us it
offers only a very limited scaffolding. Kubebuilder has strong opinions
on where the apis should be stored (./api instead of currently used
./apis) and migrating to it should be a separate effort (if we ever
want to).

Signed-off-by: Nadia Pinaeva <[email protected]>

Author: npinaeva