OpenStack driver fails waiting on ssh in ansible 2.19

[ednxzu]

In Ansible 2.19, using the openstack driver with auto_ip: False results in an error because the "Wait for SSH" task gets null as a host to wait.

This is cause by this conditional which evaluates to False, because the task setting this value now returns None rather than an empty string.

The solution to this would be the change the conditional to when: not address | bool, which would work for both an empty string and None