renderer: fix legacy dynamic light intensity
When I fixed the legacy dynamic light renderer in #1093, I noticed the dynamic light was too faint.
Since then I noticed the light was brighter with such renderer when legacy map overbright was enforced, meaning it was the overbright cancellation that was running where it should not.
This is now fixed.
Legacy dynamic light renderer with legacy overbright (reference):
Legacy dynamic light renderer with new overbright implementation:
For comparison, this is how it looks with the non-legacy tiled dynamic light renderer:
The light is believed to be different because the lighting algorithm is totally different to begin with.
The legacy light renderer not saturating to white is believed to be because the legacy dynamic light blends the dynamic light as a separate stage and then, the light is clamped, we can't fix that easily, it's a legacy renderer anyway.
LGTM (didn't really review or test)