Change to Ubuntu for the WSL2-lima container image?

### Description

Currently we are running Fedora as the base for the WSL2 image, but Ubuntu for the VM image.

I know that Podman and Podman Machine are using Fedora because of a lack of `podman` packages.

EDIT: I am specifically talking about the WSL2 image: https://github.com/containers/podman-machine-wsl-os
They are using Fedora CoreOS (not Fedora Cloud) for the VM, but Fedora Container for the WSL2 container.

But for our default, it would be nice if it (container) was more similar to `template://default` (image)

Previously AC was struggling a bit with the systemd support, but that has now been fixed (in 0.4.1).

We also should consider making it part of the project, similar to https://github.com/lima-vm/alpine-lima
(since this is a container image as a rootfs, we want to preinstall packages rather than doing it at runtime)

* https://github.com/lima-vm/lima/discussions/3829

----

https://github.com/lima-vm/lima/blob/master/templates/experimental/wsl2.yaml

https://github.com/runfinch/finch-core/blob/main/rootfs/Dockerfile

My AC testing image was based on Debian, but that was mostly for OpenRC support...

So the suggestion is to go with the same OS, that is: `docker.io/library/ubuntu:rolling`

There is a bunch of other unneeded stuff, in the current image:

* `dnf update`
* `cosign` package
* old `qemu-user-static*`
* disabled network setup?

We only want the basic packages like sshd and sshfs, and we are not using cloud-init*

\* the container drivers are using the simplified boot.sh and the lima-init script instead