Remove unusued create_test_server

Create_test_server call should be removed from
test_server_groups_rbac as it's unused [0].

[0] https://github.com/openstack/patrole/blob/fba3135950e7cba2a2bffae5927831835b93b754/patrole_tempest_plugin/tests/api/compute/test_server_groups_rbac.py#L33

Change-Id: Ie5c568f5874e14581c4a64e4d79e002eff65c9cc
Closes-Bug: #1699416
diff --git a/patrole_tempest_plugin/tests/api/compute/test_server_groups_rbac.py b/patrole_tempest_plugin/tests/api/compute/test_server_groups_rbac.py
index ff79684..f9b065c 100644
--- a/patrole_tempest_plugin/tests/api/compute/test_server_groups_rbac.py
+++ b/patrole_tempest_plugin/tests/api/compute/test_server_groups_rbac.py
@@ -29,11 +29,6 @@
             msg = "%s skipped as os-server-groups not enabled." % cls.__name__
             raise cls.skipException(msg)
 
-    @classmethod
-    def resource_setup(cls):
-        super(ServerGroupsRbacTest, cls).resource_setup()
-        cls.server = cls.create_test_server(wait_until='ACTIVE')
-
     @rbac_rule_validation.action(
         service="nova",
         rule="os_compute_api:os-server-groups:create")