Fix challenges for last Spartan standing

It says you can leave the match after you get out but I’ve only received credit for my challenges for this game mode when I win. Each time I left after receiving the message that I can leave now, none of it counted towards challenges. And in addition to this the XP booster doesn’t seem to be working either. I used three and none of them would double any of the completed challenges.

So far between the challenges not working and the mangler being crappy now, I’m about as impressed as I anticipated.