cleanup: prevent panic in cleanUpSnapshot
cleanup: prevent panic in cleanUpSnapshot

While cleaning up snapshots, not all object may exist after a partial
provisioning attempt. In case objects are missing, do not try to delete
them.

Fixes: #2192
Signed-off-by: Niels de Vos <7bda0c0ee7f47171cc808e9e60292cbc5d8140dd@redhat.com>

ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi,ceph/ceph-csi