Update variable template placeholder values

Created by: slifty

Our ansible scripts all have variable templates for local installs, and part of running the scripts is populating the templates with real values. This PR replaces the placeholders in those tempaltes so that it becomes possible to use envsubst.

This change should have no impact on any deployed site (since we are just modifying placeholders in templates), but also this shouldn't even change deployment practices since these placeholders can be just as easily populated manually as the other format.