SH-862 FIX re-scaling render weight algorithm

We were double-counting the factor of scale both through
the streaming cost algorithm, as well as another multiplier
in the render cost algorithm. This caused objects at small scales
to have little cost difference regardless of amount of geometry,
due to minimum costs.

Eliminated extra scale factor, and instead scaled number of triangles
up by a constant factor to keep the balance between geometry and texture
costs sane.