The kinds of auto delete behavior to use when snapshot
reserved space is full.
Values:
SNAPSHOT_AUTO_DELETE_BEHAVIOR_UNSPECIFIED (0):
The unspecified behavior.
DISABLED (1):
Don't delete any snapshots. This disables new
snapshot creation, as long as the snapshot
reserved space is full.
OLDEST_FIRST (2):
Delete the oldest snapshots first.
NEWEST_FIRST (3):
Delete the newest snapshots first.
