Split resource_setup for compute tests

Split up the resource_setup method for all the compute tests, as per the
latest spec.

Partially-implements bp:resource-cleanup

Change-Id: I6562534ca5eb5e33c6f8d6cbcac5e7735535916a
diff --git a/tempest/api/compute/servers/test_servers.py b/tempest/api/compute/servers/test_servers.py
index 624d9c2..8668d1a 100644
--- a/tempest/api/compute/servers/test_servers.py
+++ b/tempest/api/compute/servers/test_servers.py
@@ -21,8 +21,8 @@
 class ServersTestJSON(base.BaseV2ComputeTest):
 
     @classmethod
-    def resource_setup(cls):
-        super(ServersTestJSON, cls).resource_setup()
+    def setup_clients(cls):
+        super(ServersTestJSON, cls).setup_clients()
         cls.client = cls.servers_client
 
     def tearDown(self):