[DRE-maint] Bug#887085: systemd units are pushed to salsa

[Pirate Praveen]

The systemd units are pushed here

https://salsa.debian.org/ruby-team/diaspora-installer/-/commit/c40f18f363a35a967690e8bbff382330638b2755

We currently use debhelper compat 10 for this (like gitlab), but we 
need to find out how to do it in newer debhelper compat versions.

Another thing is we need to properly manage /etc/diaspora.conf 
migration to /etc/diaspora/diaspora.conf and find a way to export these 
variables for the init script (gitlab does that already and we can use 
the same strategy here).