The test relied on moving `initrd` secrets from the store into the
`initrd` which was fine here as it's only an integration test and not a
production environment.
However, this broke in 20.09 when support for this was dropped[1]. To make
sure that the snakeoil key used as hostkey for `sshd` here actually gets
copied into the VM, I added a small script for this that takes care of
this process while building the initial ramdisk.
[1] d930466b77
819b0f4bb8