Patterns On Landscape Spline Normals

On higher-density Landscapes, Landscape Splines can lead to patterned artifacts in the geometry normals.

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

1. Download the Licensee's test project and open (see addl info URL)
2. Observe the lines, dots, chevrons, and other patterns on the geometry normal on the landscape spline revealed by the specular highlight
BugItGo 10418.910247 5190.412439 3023.649215 -59.200101 -174.450002 0.000000
3. Create a new Landscape with the default settings, add a chrome Material, and a spline.
4. Observe there are no artifacts
5. Create a new Landscape with the following settings, add a chrome Material, and a spline.
Scale: 12,12,100
127x127 Quads
20x20 Number of components
Overall Resolution: 2541x2541
6. Observe the same artifacts