Comment # 3 on bug 1065551 from David Disseldorp

In the meantime, Andreas has also fixed this upstream via:
https://bugzilla.samba.org/show_bug.cgi?id=13129

...the upstream fix adds a required --no-process-group parameter to the systemd
service files, and also adds support for running the s4 Samba daemon in the
foreground.

We really should just drop the downstream service files and migrate to upstream
- we could use X.service.in templates for handling cross-distro path
differences.