Skip emerald bounce logic in intermission ticker on dedicated

Uncapped moved some of the intermission's emerald bouncing logic to Y_Ticker, which caused dedicated servers to execute it as well. However, when a special stage is failed, there's a check for data.spec.emeraldy < (vid.height/vid.dupy)+16, which ends up causing a division by 0 for the dedicated server.

This branch also fixes a regression where disabling the intermission emeralds would still play their sounds.