The aggregate.remove_host.start and aggregate.remove_host.end notifications
has been transformed to the versioned notification framework.
Note that the legacy event_type was aggregate.removehost but the versioned
notification is named to aggregate.remove_host to keep the naming consistent
with the other event_types.
Implements: bp versioned-notification-transformation-queens
Change-Id: I5cb84eb797ca98964a04b5b495fba263db98a54f