tests: skip rgw_tuning_pools_are_set when rgw_create_pools is not defined

since ooo_collocation scenario is supposed to be the same scenario than the
one tested by OSP and they are not passing `rgw_create_pools` the test
`test_docker_rgw_tuning_pools_are_set` will fail:
```
>       pools = node["vars"]["rgw_create_pools"]
E       KeyError: 'rgw_create_pools'
```

skipping this test if `node["vars"]["rgw_create_pools"]` is not defined
fixes this failure.

Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>

tests/functional/tests/rgw/test_rgw_tuning.py

@@ -42,7 +42,9 @@ class TestRGWs(object):
             cluster=cluster
         )
         output = host.check_output(cmd)
-        pools = node["vars"]["rgw_create_pools"]
+        pools = node["vars"].get("rgw_create_pools")
+        if pools == None:
+            pytest.skip('rgw_create_pools not defined, nothing to test')
         for pool_name, pg_num in pools.items():
             assert pool_name in output
             pg_num_str = "pg_num {pg_num}".format(pg_num=pg_num["pg_num"])