Compute HA: Remove version discovery of keystone API
Compute HA: Remove version discovery of keystone API

Keystone removed its v2 API a long ago and now it provides v3 API only.
Thus we no longer need any logic depending on Keystone API version.

Change-Id: Ifffe5bea246478954f86e803f8038d73f039eaf8

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates