Tweak Cockpit 'Join Domain...' click
    
    Always do the page-down thing, having it conditional just makes
    things more complicated unnecessarily. Try up to 5 times to
    click the link, because Cockpit sometimes redraws itself before
    us identifying it and clicking on it, e.g.:
    https://openqa.fedoraproject.org/tests/968422
    
    Signed-off-by: Adam Williamson <awilliam@redhat.com>