Values:
STATE_UNSPECIFIED (0):
The Backup resource is in the process of
being created.
CREATING (1):
The Backup resource has been created and the
associated BackupJob Kubernetes resource has
been injected into the source cluster.
IN_PROGRESS (2):
The gkebackup agent in the cluster has begun
executing the backup operation.
SUCCEEDED (3):
The backup operation has completed
successfully.
FAILED (4):
The backup operation has failed.
DELETING (5):
This Backup resource (and its associated
artifacts) is in the process of being deleted.
