Set validate_host parameters in site-variables
Set validate_host parameters in site-variables

We have a todo list item to pull these from site-variables, get that
done. With this, our base pre playbook is pretty copyable if someone
wanted to.

Change-Id: Icfd1d416a9f4520775b6e33c4055dbd223600cbb

openstack-infra/project-config,openstack-infra/project-config