Incorrect Pyramid levels when using LocalLayoutScheme

Describe the bug

When creating a Pyramid that uses 'LocalLayoutScheme', for an RDD where the extent is not nicely aligned to the LayoutDefinition, lower zoom levels are corrupt.

Example screenshot

(Those white vertical strips are not supposed to be there)

To Reproduce

I experienced this with this code:
https://github.com/Open-EO/openeo-geotrellis-extensions/blob/b38029ac83e671e70ff85b15e055d6f696c11641/openeo-geotrellis/src/main/scala/org/openeo/geotrellis/geotiff/package.scala#L179
Reproducing it in a unit test was more difficult, because the RDDs in my tests are too well aligned.

I personally solved it by using a custom layout scheme, which simply multiplies the cellsize with a factor 2, which aligns better with halving tile sizes:
https://github.com/Open-EO/openeo-geotrellis-extensions/blob/f3fcb0ec13aa6048773aea283aa1eb14c8a0791e/openeo-geotrellis/src/main/scala/org/openeo/geotrellis/geotiff/package.scala#L174

This may also be better behavior for the LocalLayoutScheme included in Geotrellis?

Expected behavior

Correct overviews

Environment

• Java version: 1.8
• Scala version: 2.11
• GeoTrellis version: 3.6

Start with LocalLayoutScheme and the reproduction code in openeo-geotrellis-extensions/src/main/scala/org/openeo/geotrellis/geotiff/package.scala, especially the referenced lines. Investigate how unaligned RDD extents are handled at lower pyramid levels and compare with the custom layout scheme described there. Done means overviews no longer contain the reported white vertical strips, ideally with a reproducible unit test.