[DRE-maint] Bug#853161: #853161: All workers run as one systemd unit

[Riku Voipio]

Hi,

> obs-worker is a, well, not very nice init script which runs all the
> worker instances (under screen of all things).

Digging under the hood, adapting this initscript to the brave new world
doesn't perhaps make much sense. The initscript downloads bs_worker from
obs server and starts it with a handful of parameters:

https://github.com/suihkulokki/obsworker/blob/master/start-obsworker

Similar approach would probably work on systemd service, although one
might need to provide upstream with a "quiet" mode so that bs_worker
doesn's spam the logs full of build lines...

The real complexities in the initscript come from the various VM support
options. Which is probably something that shouldnt really be done from
initscripts.

Riku