Simplify BURST_FRAME_FAERIE_MYSTIC_FIRE animation WML even further

Instead of using empty duration=1 frames to preclude anticipated [frame]
image rendering, we can use an empty frame (duration=0) and scrap the
odd start_time=-1 value.
Simplify animation WML for the Verlissh Control Spire unit type
Discard the halo positioning shift for chaos-halo*.png for the Control Spire

It looks bad, and testing shows that chaos-halo*.png and
chaosmissile*.png actually fit well together with automatic centering.