Use StandardInput=tty when AUTORELABEL=0
    
    selinux-autorelabel service can be configured to drop to a shell to allow
    administrator to manually relabel a filesystem, see selinux_config(5). In
    this case, the service needs to have a tty attached to stdin. Given that
    tty should not be attached to the service by default, see
    https://bugzilla.redhat.com/show_bug.cgi?id=1634661 , the
    selinux-autorelabel-generator.sh will configure the service to attach
    tty only if AUTORELABEL=0
    
    Resolves: rhbz#2165508