Restrict Volume type deletion with volumes assoc

Updated the delete_volume method to wait till the
volume is deleted before type is delted.

Closes-Bug: #1215329

tag:doc-impact

Change-Id: I7a5d4b473588757d21b461337df493e8046e1d09
diff --git a/tempest/api/volume/admin/test_volume_types.py b/tempest/api/volume/admin/test_volume_types.py
index 822f691..b15f8dd 100644
--- a/tempest/api/volume/admin/test_volume_types.py
+++ b/tempest/api/volume/admin/test_volume_types.py
@@ -41,6 +41,7 @@
     def _delete_volume(self, volume_id):
         resp, _ = self.volumes_client.delete_volume(volume_id)
         self.assertEqual(202, resp.status)
+        self.volumes_client.wait_for_resource_deletion(volume_id)
 
     def _delete_volume_type(self, volume_type_id):
         resp, _ = self.client.delete_volume_type(volume_type_id)