Revert "Let r_AmbientScale scale the outgoing diffuse light."

This reverts commit 2f89a596972d1367e345f714f3e4f15573b85d8b.

Revert "Reactivate r_ambientScale and r_normalScale cvars."

This reverts commit 0a13b9a7fe588b36256b42abb679ba3c1ae63af7.

Revert "Merge branch 'for-0.25' into vertpack"

This reverts commit 16f0cfdc02d74cad669d1ae5452ed17cda248949, reversing
changes made to a9c941f63ab538d35efb02ffd14bcfd22dbaf2d7.