Run setup_login() while creating the installer OS too, in order to
disable passwordless root login.
Note that this may sound like a security flaw, but it isn't.
* setup_login already ran for the target OS, meaning after the
installation is done, one is not be able to login as root without
password
* root login without password was only possible via serial console (or by
attaching a keyboard), not via SSH
* getting root rights via serial in the installer OS is actually desired
for debugging, we add a debug user with sudo set up by default:
https://wiki.postmarketos.org/wiki/On-device_installer#Debug_user
So even though this isn't a problem, disable it to avoid confusion.
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