Add alternative cockpit "updated" needle
    
    When we have to restart Cockpit during the update, we don't get
    the usual "successful" screen after logging back in, we'll have
    to match on something indicating an update did happen. I wanted
    to use the little icon next to the package count but it seems to
    have some kind of problem with anti-aliasing or something, I've
    created two needles for it and neither matched on the next run
    of the test. So let's match on this "reboot needed" text instead,
    I hope it'll always be there when we hit this case.
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>