Move common code from osmo-*-master to debian-stretch-build and
* add the OBS repository key (debian only)
* add the OBS repository with "nightly" feed (debian only, already done
* install telnet
* invalidate the cache once the repository is updated
While at it, remove deprecated MAINTAINER lines.
This fixes the need to read both the repository index of debian-stretch
and centos8 and having to invalidate the cache if either of them changes
(instead of reading just the relevant index and invalidating the cache
only if the relevant one changes).
A similar change was done with osmo-*-latest in
Using a separate container will allow us to do gbproxy specific things
like waiting for physical net-devices to show up in the docker netns
before actually starting the osmo-gbproxy executable