underwater CEG effects are visible when flying over them

submarine wake/bubble CEG effects are visible when you fly over them!

the used CEG effects:
https://github.com/beyond-all-reason/Beyond-All-Reason/blob/master/effects/bubbles.lua

Start with effects/bubbles.lua to understand the submarine wake and bubble CEG definitions, then reproduce the effect while flying over the underwater area. Trace the engine's CEG rendering path to determine why the effects remain visible from above; done means they are hidden when viewed through the water from above while still appearing underwater.

Written by the indexing model from the issue text.