Code review comment for ~thibf/uvtool:thibf/uvt-kvm_wait_system_booting

Thanks!

I tested this and noticed that the nologin output appears on the terminal, which is sub-optimal, but that seems like a bit of a rabbithole to fix and we've iterated long enough, so I'm going to merge this as-is. Especially since the cloud-init regression that exposed this (valid) uvtool bug is also planned to be fixed soon, so this will only be temporary for users of Ubuntu stable releases in practice anyway.

We could refactor this in the future to capture the message and replay it unless detecting this condition or something like that.

Next, this needs to be uploaded to Ubuntu and SRU'd.