Update our Vagrant ISO build basebox wrt. vagrant-libvirt

If we merged #11972 (closed) as is, the builds on Jenkins would last about 20% (~17 minutes) longer. It seems that ~5 minutes, from the added build time, comes from upgrading the basebox. Let’s please not do that on every ISO build on Jenkins => let’s please update the basebox before we deploy #11972 (closed).

Feature Branch: feature/11980-static-build-env

Parent Task: #11972 (closed)

Original created by @intrigeri on 12017 (Redmine)