Refactored Tests to load scenarios from file

In this changeset, I simplified the logic that is used to create
cluster data model scenarios.

Change-Id: Ia6e138d9897190d3207a70485dc62ccc34087686

watcher/tests/decision_engine/model/test_mapping.py

@@ -20,8 +20,7 @@ import uuid
 
 from watcher.decision_engine.model import element
 from watcher.tests import base
-from watcher.tests.decision_engine.strategy.strategies import \
-    faker_cluster_state
+from watcher.tests.decision_engine.model import faker_cluster_state
 
 
 class TestMapping(base.TestCase):