magnum domain register error at setting domain id
magnum domain register error at setting domain id

Setting up Magnum fails at creating and setting magnum's trustee
domain.
The changes this patch introduces follow.
  - add registering trustee_domain
  - remove unnecessary set_fact as this variable is used only once

Change-Id: I1c1ed8a20871fb4e9f153c6dd1431d9b6fd286a5
Closes-Bug: #1667209

dardelean/kolla-ansible,dardelean/kolla-ansible,dardelean/kolla-ansible