Retract GrFillRectOp from GMs and tests

Bug: skia:11837
Change-Id: I150d9b3debd3ebc7885720a5a287a89bf0e3f0de
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/425019
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
8 files changed