Fix#61859.
Assertion fails when a Google Compute Engine image is built, because
now choices of filesystem types are restricted to `f2fs` and `ext` family if
auto-resizing is enabled.
This change will pin the filesystem used on such an image to be `ext4` for now.
Use googleOsLogin for login instead.
This allows setting users.mutableUsers back to false, and to strip the
security.sudo.extraConfig.
security.sudo.enable is default anyhow, so we can remove that as well.
