Foliage lightmaps for LODs does not look correct

When using the foliage tool with any mesh that has a LOD the lightmap generates artifacts for the instance. The base LOD will have correct looking lightmaps, however when pulling back and seeing the lower LODs will wrong looking lightmaps generated.

Looking at this with the attached example FBXs the LOD1 looks like it's using the Lightmap 0 while Lightmap 1 is used by LOD0. If I set the Lightmap Coordinate Index to 0 and use that as the lightmap coordinate, everything looks correct, but this doesn't work well if you need a specific texture UV setup instead of just having it flat mapped like I do.

Tested in:

1. 4.6.1 CL-2386410
2. 4.8.3 CL-2634408
3. 4.10.4 CL-2872498
4. 4.11.2 CL-2946394
5. 4.12.3 CL-3013449
6. 4.13 Dev-Editor CL-3018237

This is like this in all builds tested above, so this isn't a regression with this feature.

1. Open UE4
2. Import or use an asset that has a LOD (Two meshes attached below)
3. Add the SM to the Foliage tool list of asset
4. Paint a few around
5. Build Lighting in a default scene (will be a stationary directional light)
6. Move close and further away from mesh to see the LOD transition.

Regression: No

Results: The lower LODs for foliage don't seem to get a useful lightmap.

Expected: The lightmap shouldn't have the artifacts present that make it very noticeable with the LODs.