game engine: Revert to using regular gimpact for mesh shapes

This reverts part of r53019.
While the compound shape trick works well in some cases, overall it's
much slower and even causes crashes under certain conditions.

We could make this and option and fix the crashes, but it's better to
implement convex decomposition anyway so just reverting for now.

Fixes [#34353] Ray cast on Triangle mesh bounded Rigid Body Object causes blender crash to desktop without error.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@54757 954f8c5b-7b00-dc11-b283-0030488c597c