[2022] Adjusting Mythic Dungeon Difficulty

We are fixing an issue with the difficulty of Mythic Dungeons (Mythic 0) not being increased by the intended amount with the start of Season 3, which has caused an unintended difficulty gap between Mythic 0 and Mythic +2.

After the change goes live momentarily, it should help make advancing from Mythic 0 dungeons into attempting Keystones feel smoother and less of a big jump in difficulty.