Ejected users due to permission check cannot rejoin meeting

 - users who are ejected from meeting because of permission check cannot
   rejoin meeting as we mark them as banned. Only users ejected by a
   moderator should be banned. Later on, we should make the moderator
   indicate if the ejected user should be bannd or not.

   see https://github.com/bigbluebutton/bigbluebutton/issues/9608