Shadows around chunk borders over water

Release 439604

Summary:
When smooth lighting is active, thin shadows appear in a patchwork checkerboard across chunks that weren't loaded when opening the world or un-minimizing the client.

Impact:
Low priority / Cosmetic, noticeable on Relics of the Privateers due to large amounts of water.

Repro Steps:
1. Load a map with an ocean (E.g. Relics of the Privateers)
2. Ensure smooth lighting is enabled.
3. Fly towards an ocean or large patch of water not originally loaded. (E.g. position 314 96 284 on Relics)
4. Observe patchwork lines on the water.

Observed Results:
The ocean will be covered with a semi-random lines of shadow that are very visible from the air, that correspond with chunk boundaries. Updating the terrain does not permanently remove them, as they appear again when the area is left and revisited.

Expected Results:
Correct lighting with no obvious artifacts.

Screenshots/Videos attached: Yes, an example of the shadow patches.