pybind/ceph_volume_client: Update the 'volumes' key to 'subvolumes' in auth metadata...

pybind/ceph_volume_client: Update the 'volumes' key to 'subvolumes' in auth metadata file

The older auth metadata files before nautilus release stores
the authorized subvolumes using the 'volumes' key. As the
notion of 'subvolumes' brought in by mgr/volumes, it makes
sense to use 'subvolumes' key. This patch would be tranparently
update 'volumes' key to 'subvolumes' and newer auth metadata
files would store them with 'subvolumes' key.

Also fails the deauthorize if the auth-id doesn't exist.

Fixes: https://tracker.ceph.com/issues/49294
Signed-off-by: Kotresh HR <khiremat@redhat.com>