Remove User= and Group= from systemd service files

Service files of Osmocom programs will have User= and Group= in the
future, so these don't run as root. It was decided that for OE-based
systems, we will still run them as root for now.

Related: OS#5684, OS#4107
Change-Id: I68a8fba034aeb0e2923b2958b8d6842410d8b23c
11 files changed