As we found a while back (T339231), the kubelet partition (/var/lib/kubelet) is too small by default (30G), and when using LLMs, we can actually run out of disk space there.

Tweak the k8s specific overlay config (modules/install_server/files/autoinstall/partman/custom/kubernetes-node-overlay.cfg) to increase the disk space for that partition so we don't have to manually tweak it after every (re)install.

Since this use case is unique to use, make a copy of the partman overlay mentioned above and wire it into our config (via modules/profile/data/profile/installserver/preseed.yaml)

120G should probably be enough.