Remove layer-coverage-tracking experiment

This effectively reverts reviews.skia.org/122000

Bug: skia:10987
Change-Id: I989241110f17c0e3c2a896aea4bc2bc4cc8c910f
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/472801
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
10 files changed