[Impeller] Better demonstrate blur and draw picture? (#45388)

The current goldens are changing a lot, this should be stabler. though not sure if it looks quite right.

Author: Jonah Williams

impeller/aiks/aiks_unittests.cc

@@ -3127,7 +3127,8 @@ TEST_P(AiksTest, CanCanvasDrawPictureWithAdvancedBlend) {
   auto picture = subcanvas.EndRecordingAsPicture();
 
   Canvas canvas;
-  canvas.Translate({200, 200});
+  canvas.DrawPaint({.color = Color::Black()});
+  canvas.DrawCircle(Point::MakeXY(150, 150), 25, {.color = Color::Red()});
   canvas.DrawPicture(picture);
 
   ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));
@@ -3143,13 +3144,14 @@ TEST_P(AiksTest, CanCanvasDrawPictureWithBackdropFilter) {
                       });
   auto image = std::make_shared<Image>(CreateTextureForFixture("kalimba.jpg"));
   Paint paint;
-  paint.color = Color::Red();
+  paint.color = Color::Red().WithAlpha(0.5);
   subcanvas.DrawImage(image, Point::MakeXY(100.0, 100.0), paint);
 
   auto picture = subcanvas.EndRecordingAsPicture();
 
   Canvas canvas;
-  canvas.Translate({200, 200});
+  canvas.DrawPaint({.color = Color::Black()});
+  canvas.DrawCircle(Point::MakeXY(150, 150), 25, {.color = Color::Red()});
   canvas.DrawPicture(picture);
 
   ASSERT_TRUE(OpenPlaygroundHere(canvas.EndRecordingAsPicture()));