Set up noble staging job

[legoktm]

Description

We're pretty close to having a working noble install, so we should set up a staging job to verify it.

I naively tried setting up a noble CI staging job previously, it didn't work and really didn't even get very far. The bento/ubuntu-24.04 box appears to be a "version 2" box as described at https://vagrant-libvirt.github.io/vagrant-libvirt/boxes.html#box-formats. Running it with our old-ish vagrant version turns into "No image virtual size specified for box" (which is technically correct, it's not in the metadata.json file). Note that we can't easily upgrade to the latest version of vagrant because of the licensing change.