Preview weight on Landscape Layer Sample affects Grass Output on landscape disregarding layer info

Preview weight on Landscape Layer Sample affects Grass Output on landscape disregarding layer info

Repro Rate: 3/3

Tested this in //UE4/Release-4.27 @ CL#18319896 and the issue did NOT occur there, it is a regression.

1. Create a new Blank BP project
2. In the content browser, create a new Landscape Grass Type (Right-Click > Foliage)
3. Open and assign Grass Mesh to SM_Bush for the first index of the Grass Varieties array
4. Create and open a new Material
5. Place a Grass output node down
6. Assign your Grass Type to the array.
7. Add a LandscapeLayerSample node
8. Set the Preview Weight to 1.0
9. Connect the LandscapeLayerSample to the Grass output node
10. Save & Apply then close the Material Editor
11. Add a landscape with "Enable Edit Layers" enabled and your created Material assigned to it.

Results: Landscape generates with grass applied to the entire landscape.
Expected: Landscape generates having no grass, with the preview weight having no effect in-scene.