launch: start transient units as the correct user
launch: start transient units as the correct user

We need to pass the User option to systemd to get the transient unit started
as the correct user. Now they were always run as root, which apart from obviously
not being what we want, caused some services to be able to claim their name, as
the policy specified a non-root user.

Report: <https://bodhi.fedoraproject.org/updates/dbus-broker-8-1.fc27#comment-699753>
Signed-off-by: Tom Gundersen <7c8224529a7c718e876cb2496c973509fde1e50e@jklm.no>

bus1/dbus-broker