{{role.name}}ExtraGroupVars (e.g. ControllerExtraGroupVars) is a new
interface to override any Ansible group var for a specific role.
If the group var was already defined in a service, the ExtraGroupVars
will override it.
Depends-On: https://review.opendev.org/717170
Change-Id: I3115ea3b1bd14979bad5e2ed45e91107ee969ca9