Use SkPaint.nothingToDraw instead of PaintUtils helper.

The PaintUtils helper is now shared between all pipelines and was
missing a quick reject test for drawLoopers which are used in
view.setShadowLayer and supported in the Skia pipelines.

Bug: 35809097
Test: added hwui unit test and verified in DocumentsUI app
Change-Id: I3c4a988f1c42b7f421f78ac3659af1daee910ea2