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_instance_actions.py b/tempest/api/compute/servers/test_instance_actions.py
index b00221c..c804170 100644
--- a/tempest/api/compute/servers/test_instance_actions.py
+++ b/tempest/api/compute/servers/test_instance_actions.py
@@ -20,9 +20,13 @@
 class InstanceActionsTestJSON(base.BaseV2ComputeTest):
 
     @classmethod
+    def setup_clients(cls):
+        super(InstanceActionsTestJSON, cls).setup_clients()
+        cls.client = cls.servers_client
+
+    @classmethod
     def resource_setup(cls):
         super(InstanceActionsTestJSON, cls).resource_setup()
-        cls.client = cls.servers_client
         server = cls.create_test_server(wait_until='ACTIVE')
         cls.request_id = server.response['x-compute-request-id']
         cls.server_id = server['id']