use osbuild from supermin

[cgwalters]

A while ago in the interest of sharing code with osbuild/image builder we just started shipping the RPM package, see

coreos-assembler/src/deps.txt

Line 23 in 7fa68d0

# osbuild-composer

(which got temporarily disabled, we could probably re-enable)

But anyways what I then got stuck on is the giant impedance mismatch between osbuild wanting to run as root as a systemd service versus coreos-assembler wanting to run as an unprivileged container with /dev/kvm.

But @dustymabe mentioned the idea we could start running osbuild code inside a supermin vm, I think basically replacing our create_disk.sh script.

[cgwalters]

Discovery: The CentOS Automotive pipeline has code to run osbuild in qemu: https://gitlab.com/CentOS/automotive/sample-images/-/blob/main/osbuild-manifests/osbuildvm/osbuildvm?ref_type=heads

[dustymabe]

This was done in #3643

osbuild is being run in our pipelines via a supermin VM.