Comment 12 for bug 1743718

A fix for this is queued up for when a few more apparmor issues got an ack upstream so I can deal with them in one upload.

Until that feel free to review [1].
It includes the old code plus:
- creation for an own group (after discussion with Seth on the sprint)
- upgrade from Xenial will fix the old group to the new one
- remove user/group on purge

[1]: https://git.launchpad.net/~libvirt-maintainers/ubuntu/+source/libvirt/commit/?h=ubuntu/bionic-4.0&id=5dfa2589f20cc2f16c8b5d1952272c9e945d84fa