Remove redundant checks of stack status

The main methods create/update/delete in HeatIntegrationTest class
already contains _wait_for_stack_status, so we can remove duplicate
checks in tests.
Also was added paramter enable_cleanup for stack_create method, which
allows to disable CleanUp method in tests, where we delete stack
manually.

Change-Id: I41b546d648656676ec9bc3b38940eac68f9a848d
diff --git a/scenario/test_volumes.py b/scenario/test_volumes.py
index 79d4931..7562304 100644
--- a/scenario/test_volumes.py
+++ b/scenario/test_volumes.py
@@ -61,8 +61,7 @@
 
         # Delete the stack and ensure a backup is created for volume_id
         # but the volume itself is gone
-        self.client.stacks.delete(stack_id)
-        self._wait_for_stack_status(stack_id, 'DELETE_COMPLETE')
+        self._stack_delete(stack_id)
         self.assertRaises(cinder_exceptions.NotFound,
                           self.volume_client.volumes.get,
                           volume_id)
@@ -97,8 +96,7 @@
                          testfile_data)
 
         # Delete the stack and ensure the volume is gone
-        self.client.stacks.delete(stack_identifier2)
-        self._wait_for_stack_status(stack_identifier2, 'DELETE_COMPLETE')
+        self._stack_delete(stack_identifier2)
         self.assertRaises(cinder_exceptions.NotFound,
                           self.volume_client.volumes.get,
                           volume_id2)