See https://github.com/ostreedev/ostree/issues/3503

We have a longstanding bug where systemd tries to detach the LUKS device for the rootfs during shutdown. This ordinarily is mostly a cosmetic issue because we're doing a full reboot and flushing all state.

But for enabling soft reboots having a clean shutdown matters.

Basically please change the blivet (right?) code to add `x-initrd.attach` to /etc/crypttab device for the rootfs `/`.