* image: remove autologin via mkosi
In mkosi v24 --autologin no longer works for ttyS consoles. Since the CSPs use those exclusively for their serial consoles, we need to replace this with another solution (see next commit)
* image: add getty systemd unit for debug images
This replaces the mkosi --autologin solution with a getty systemd unit for ttyS0.
Note that both console and debug images hace their consoles enabled.
