tests: skip rgw_tuning_pools_are_set when rgw_create_pools is not defined

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>
(cherry picked from commit 1c3dae4a90816ac6503967779b7fd77ff84900b5)