Temporarily use an offset RenderEffect for the stretch overscroll.
This makes it possible to visually validate the effect and start
writing CTS tests to ensure it is functioning.
Bug: 178807038
Test: Iab32812bfa626ae6932f52c1a9af78069b5dc6ac
Change-Id: I5b0da0e669d36f4149cd58b4b3aff149a1fa7e14