Fix skip of octavia-undercloud Ansible role
Fix skip of octavia-undercloud Ansible role

The migration of Octavia to external_deploy_task [1] changed the
undercloud group name from 'undercloud' to 'Undecloud' in line with [2].
Due to that, the execution of role octavia-undercloud was being skipped
as no host pattern could be matched.

[1] https://review.openstack.org/#/c/559374/
[2] https://review.openstack.org/#/c/588075/

Closes-Bug: #1786786
Depends-On: https://review.openstack.org/580119

Change-Id: I50720c2f1bdb8dce92e297c4d6bfac716bb85b89

openstack/tripleo-common,openstack/tripleo-common