The Keystone project is removing v2 API code (see [1]). puppet-tempest
should reflect that by not enabling this API by default, and using
v3 as the default value for auth_version.
[1] - https://review.openstack.org/#/q/topic:bp/removed-as-of-queens
Change-Id: I558e91cddb0e191de4874174e7774c2ec29d26ae