TripleO composable roles are working, remove old comment
TripleO composable roles are working, remove old comment

The comment is a leftover from the time when tripleo composable roles
were not supported, which was before OSP12 (!).
The comment should have probably removed when their support was merged
in https://review.gerrithub.io/c/redhat-openstack/infrared/+/383263
(I8f2efb83540c2170e3b7cd387c5ab37c8b65542f).

Also, mark the old way as deprecated in the task name, so that it is
clear that people want to look at the templates/tripleo_roles
more than templates/composable_roles for all modern use cases.

Change-Id: I9911344dcc093ba6fe220a5691bddb92087ae7e6

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared