Not entirely sure when it got broken this time, but when creating a VM
network with `nixos-build-vms(8)`, there are should be the following scripts:
* `$out/bin/nixos-test-driver` which drops into an interactive shell to
interactively perform test steps.
* `$out/bin/nixos-run-vms` which non-interactively starts the VMs from
the network so that one can manually play around in the VM.
The latter also starts an interactive shell for a while now which means
that it does the exact same thing as `nixos-test-driver` which is not
its purpose.
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