SCI: Fix bug #3614566 - "LSL6: ScummVM locks up at Electro-Shock room"

We now do the jumpToTick() for hold events after waiting for the delta
of the current event, like we do for the signal set events. This keeps
the fixes for the hold timings in QFG3, while not breaking LSL6.

Many thanks to wjp for pinpointing the actual cause of the issue.