ColorFilterLayer clips to its paint bounds

[lhkbob]

Removes use of staging flag skia_use_legacy_layer_bounds, and preserves previous behavior for ColorFilterLayers that affect transparent black by clipping before the saveLayer() to prevent the layer from changing all transparent black pixels on the canvas. Adds a unit test to make sure the display list is modified appropriately in that case.

https://bugs.chromium.org/p/skia/issues/detail?id=12083

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[lhkbob]

Closing this PR in favor of #41940, which just removes the staging flag and does no additional workaround to try and match legacy behavior. We can come back to this and CFLayer clipping if necessary.