desktop_login: tweak password typing so we wait after enter
    
    This makes it so the `wait_still_screen` that comes at the end
    of `type_very_safely` happens *after we hit enter*, not after
    we type the password but before we hit enter. I'm hoping this
    makes the 'set new password at login' more robust on aarch64, it
    seems to be failing often.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>