[Sprint/HipsterHedgehog] (fix): when deleting activity, also remove from moderated group queue

closes #504 (moved)

mentioned in merge request !222 (closed)

Can you do an event hook, listening for delete instead. Newsfeed.php is already too big with too much logic, and we have the events already

added StatusRequires Changes label

added 1 deleted label

@eiennohi please chase these MR's up..

@markeharding I actually forgot to close this MR, but we talked about this a few weeks back: I initially thought this feature was broken, as it didn't work when I tested it, but when you asked me to refactor this MR, I noticed this piece of code was already in place, and it was working: https://gitlab.com/minds/engine/blob/master/Core/Groups/Events.php#L109-126

closed