[impeller] gaussian blur has shimmers when scaling the sigma #149781
Description
This was introduced in flutter/engine#53130. The tests we have aren't good at catching motion regressions. We may want to revert that pr, but it does fix other issues where the shimmering isn't a factor like blurring solid colors (ex: shadows).
AiksTest.GaussianBlurRotatedAndClippedInteractive is a good one to see it on.