#6030 Regression fix: CreateEffectWarhead

CreateEffectWarhead effect location and water impact sound.

Closes #6164, #6165.

Removed support of ```int[] Size``` for CreateEffectWarhead, since I now realise it is a terrible idea to try and standardise it with the other three non-damage warheads.
If that functionality is needed, it would have to use range offsets rather than tiles, since an explosion can be non-centered.
I believe the OpenRA style convention is to always use var when possible, instead of string, int etc.