The choice for backup_source are:
- Backup CR
- PVC
This current prevents to create an AWXRestore CR with the Backup CR value
from the OLM UI.
Error "Unsupported value: "Backup CR": supported values: "CR", "PVC"" for
field "spec.backup_source".
Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>