Debian packaging updates

[martinpitt]

Cockpit was synced to Ubuntu now, and its autopkgtest fails. When I wrote it, I only tested this on Debian. Now fixed and tested on both.

cockpit-ws still ran as root, unlike wit the RPMs where it runs as unprivileged system user. Privilege reduction is rather important for security, so bring that in line with cockpit.spec.

The third commit lowers the cockpit-docker Recommends: for the "cockpit" metapackage. Right now, a failing apt-get install cockpit (due to failing installation of docker.io) gives a bad first impression, even though it's not really cockpit's fault. But docker.io has 8 (!) release-critical bugs in unstable and hasn't been in Debian testing for a fair while. On Ubuntu, docker.io is much less popular than in the Fedora/RH world (LXC/lxd is preferred there), and docker has a fair share of dependencies. So "Suggests:" sounds more appropriate to me, packaging UIs will offer it as extending functionality, but I don't see much reason to always install it by default everywhere.

[martinpitt]

This is ready to go, and I'd like it in 138 so that I can upload a clean package to Debian/Ubuntu. Thus setting "priority" label to have it on the release laundry list.

[larskarlitski]

Yep, makes sense to me. Thanks!