Consume RoleData config from config download files
Consume RoleData config from config download files

In https://review.openstack.org/#/c/525260/, we moved the creation of
various RoleData driven config files to deploy-steps-tasks.yaml, and to
consume the values from various role_data_* variables that were written in
the inventory (see https://review.openstack.org/#/c/528354/).

However, we were already downloading and saving the RoleData to separate
files via config download. We should consume from those files instead of
the inventory. That has the advantage that one can quickly modify and
iterate on the local files, and have those changes applied. That is
harder to do when these values are in the inventory, and not possible to
do when using dynamic inventory.

Since the tasks will fail trying to read from the files when not using
config-download, conditional local_action tasks that use the stat module
first verify the existence of the files before attempting to read their
contents. If they don't exist, the values fall back to whatever has been
defined by the ansible variable.

Change-Id: Idfdce6f0a778b0a7f2fed17ff56d1a3e451868ab
Closes-Bug: #1749784

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