systemd::service: Make template location configurable
systemd::service: Make template location configurable

Change-Id: I5eb61cd13045780b06826d7b3f6fa836d2511fc5

wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant,wikimedia/mediawiki-vagrant