Reportedly `systemd-run --scope` still got killed by the service
manager; see #4615. The suspected cause is that `scope` units are run by
the `systemd-run` process itself and inherit the caller's execution
environment (see systemd-run(1)). To fix this, we use a systemd
`service` unit instead, which is run and managed by PID 1 - hopefully
this will isolate us sufficiently so that we don't get terminated along
with `jellyfin.service`.
AJ Jordan
bab389114b