either delete `sudo` group or add sysusers.d entry

See https://github.com/containers/bootc/pull/1111#issuecomment-2658070199

Basically we have a sudo group just because Container Linux did and we should either:

• Delete it by default
• Add a sysusers.d entry for it

I lean a bit towards the former honestly...but of course a tricky thing is that our current main branch applies everywhere and it feels a little possibly unfriendly to just drop it by default, especially because in theory someone could be using it. But OTOH, why would you use it? It isn't actually wired up into anything...it seems like we just...made it because at one point Dusty tried to make a kickstart that used it??? In https://github.com/coreos/fedora-coreos-config/issues/4