Invalid Landscape Normals at component boundaries and subsections In Packaged Build

In UE 5.6, heightmap texture compression was introduced. The original implementation did not consider duplicate pixels along subsection and shared textures (multi-component) boundaries. As a result, the normals along the edges are incorrectly generated and show visual artifacts. This is more noticeable where there is high heightmap variation. 

Also tested on //UE5/Release-5.6/, CL: 45232827

This artifact did not reproduce on UE 5.5.

Public Forum: https://forums.unrealengine.com/t/world-partition-landscape-auto-material-issue-with-5-6-non-nanite/2652404/12

To repro in a new level:

• Create a new Open World map (this map uses landscape subsections), save as a copy
• Platforms -> Project Launcher
• Create a  Launch profile and set the default startup map and cook content to your newly saved map
• Launch, wait for the project to cook and run
• Fly around in packaged game
  Expected: No visual artifacts/seams long the landscape subsection boundaries
  Actual: Artifacts on the seams

1. Download the Licensee's test project (see addl info URL)
2. Package the project
3. Open the packaged game
4. Run "toggledebugcamera"
5. Fly to where you can see the specular reflection of the skylight on the landscape
6. Observe a square pattern, aligning with the landscape tiles. It might only be visible in the area with the spline.