Re-enable test 410 for cinder backups

This is to verify that the retries really do work.

zaza/openstack/charm_tests/cinder_backup/tests.py

@@ -74,7 +74,6 @@ def test_410_cinder_vol_create_backup_delete_restore_pool_inspect(self):
         inspect ceph cinder pool object count as the volume is created
         and deleted.
         """
-        return
         unit_name = zaza.model.get_lead_unit_name('ceph-mon')
         obj_count_samples = []
         pool_size_samples = []