Extend the timeouts for create / backup / snapshot test (#390)

On OSCI it's variable whether the test will pass as it's very close to
the timeout.  Extend it to give the test a reliable chance to pass.

zaza/openstack/charm_tests/cinder_backup/tests.py

@@ -97,7 +97,7 @@ def test_410_cinder_vol_create_backup_delete_restore_pool_inspect(self):
             self.cinder_client.volumes,
             cinder_vol.id,
             wait_iteration_max_time=180,
-            stop_after_attempt=15,
+            stop_after_attempt=30,
             expected_status='available',
             msg='Volume status wait')
 
@@ -109,7 +109,7 @@ def test_410_cinder_vol_create_backup_delete_restore_pool_inspect(self):
             self.cinder_client.backups,
             vol_backup.id,
             wait_iteration_max_time=180,
-            stop_after_attempt=15,
+            stop_after_attempt=30,
             expected_status='available',
             msg='Volume status wait')
         # Delete the volume