Add explict dependency to avoid gate unstable

Gate job is extremely unstable because [1]
This patch propose to add explict dependency before we fix the issue.

Story: 2008936
Task: 42544

[1] https://storyboard.openstack.org/#!/story/2008936

Change-Id: I97e05c3d912030dbf77218b114e9e16fb25dca97

heat_integrationtests/functional/test_create_update.py

@@ -80,6 +80,9 @@ parameters:
 resources:
   my_instance:
     type: OS::Nova::Server
+    # BUG We add dependency to avoid bug in story/2008936.
+    # And should remove this after bug fixed.
+    depends_on: data_volume
     properties:
       image:  {get_param: image}
       flavor: {get_param: flavor}