#68399 regressed with flutter/engine#21877 despite our tests.

The hole is that framework golden tests don't use the real iOS engine. Devicelab tests run against a real iOS physical device. Engine goldens are all for platform views which render on a different CALayer and the PR doesn't seem to have broken the rendering pipeline or accessibility etc, just the pixel output.

Add another simulator test (which our scenario app tests are) and perform a golden check to make sure it checks pixel output.