Use os_cache in place of no_cache

python-novaclient has deprecated number of arguments. Let's use
os_cache in place of no_cache for the client intialization in
integration tests. This seems to be failing with TypeError.

Change-Id: I25f85b89a50ef4746d2dd3b27f2a066e1746c769
diff --git a/common/clients.py b/common/clients.py
index afdc477..9949d3d 100644
--- a/common/clients.py
+++ b/common/clients.py
@@ -158,7 +158,7 @@
             service_type='compute',
             endpoint_type='publicURL',
             region_name=region,
-            no_cache=True,
+            os_cache=False,
             insecure=self.insecure,
             cacert=self.ca_file,
             http_log_debug=True)