Revert "_advisory_update: stop the graphical desktop at the start"
    
    This reverts commit 3208d15725ee25c01143dd610b84388afcd505ce and
    the two follow-ups. I'm hoping
    https://bugzilla.redhat.com/show_bug.cgi?id=2133829 is now
    resolved; this was intended to help with that (though I'm not
    sure it ever really did), and so we can hopefully ditch it, which
    simplifies this code.