Removes duplicate code autoscale_complete

Function autoscale_complete will be required by many test
cases, hence moving it to common.

Change-Id: Ie0545ad35c6704bc86b26748ae99f9c66ca5a468
diff --git a/common/test.py b/common/test.py
index 42fa43c..976ae8b 100644
--- a/common/test.py
+++ b/common/test.py
@@ -595,3 +595,11 @@
                 if len(matched) == num_expected:
                     return matched
             time.sleep(build_interval)
+
+    def check_autoscale_complete(self, stack_id, expected_num):
+        res_list = self.client.resources.list(stack_id)
+        all_res_complete = all(res.resource_status in ('UPDATE_COMPLETE',
+                                                       'CREATE_COMPLETE')
+                               for res in res_list)
+        all_res = len(res_list) == expected_num
+        return all_res and all_res_complete