Collapse host prep tasks
Collapse host prep tasks

Since plays cannot be parallelized with a free-like strategy, we should
have a single play that runs all host prep tasks rather than blocks of
plays for each defined role. By switching to this method we have a
single play that handles the host prep tasks concept that can be run all
at once across a cloud.

Change-Id: I2670840c9beac06f8b8ffc6eaecc88b9119ad298

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