Use new disko layout

[pinpox]

We are still using an outdated disko layout

Follow up on #16: #16 (comment)

[MayNiklas]

We need to consider, that we need to migrate systems that are already deployed.
In my tests, that isn't that simple: partitions are mounted by labels and the names of the labels changed.
-> there will be a solution for that, but we need to test it carefully!