Description of problem:



How reproducible:

Steps to Reproduce:
1. Run `ansible-playbook -i inventory.yaml down-containers.yaml`
2. Run `ansible-playbook -i inventory.yaml down-containers.yaml` again

Actual results:
Ansible errors:
```
TASK [Delete the containers associated with the cluster] *****************************************************************************************
fatal: [localhost]: FAILED! => {"changed": true, "cmd": ["openstack", "container", "delete", "-r"], "delta": "0:00:01.445139", "end": "2020-06-19 14:28:06.775255", "msg": "non-zero return code", "rc": 2, "start": "2020-06-19 14:28:05.330116", "stderr": "usage: openstack container delete [-h] [--recursive]\n                                  <container> [<container> ...]\nopenstack container delete: error: the following arguments are required: <container>", "stderr_lines": ["usage: openstack container delete [-h] [--recursive]", "                                  <container> [<container> ...]", "openstack container delete: error: the following arguments are required: <container>"], "stdout": "", "stdout_lines": []}
```

Expected results:
Ansible skips the task if no container is found