Revert "Respect LayerSettings::alpha in Skia-RE for buffer layers"

This reverts commit 0559ca76a3967b0a667a680b5b824b6f0c46e4eb.

Reason for revert: DroidMonitor: Potential culprit for b/174062136 - verifying through Forrest before revert submission. This is part of the standard investigation process, and does not mean your CL will be reverted.

Change-Id: I7dbd7f9ff2c0abfcd2b200b35110727c143201dc
diff --git a/libs/renderengine/skia/SkiaGLRenderEngine.cpp b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
index 032e9b9..aefedb4 100644
--- a/libs/renderengine/skia/SkiaGLRenderEngine.cpp
+++ b/libs/renderengine/skia/SkiaGLRenderEngine.cpp
@@ -678,8 +678,6 @@
             } else {
                 paint.setShader(shader);
             }
-            // Make sure to take into the account the alpha set on the layer.
-            paint.setAlphaf(layer->alpha);
         } else {
             ATRACE_NAME("DrawColor");
             const auto color = layer->source.solidColor;
@@ -826,7 +824,7 @@
     ATRACE_CALL();
 
     SkPaint paint;
-    paint.setAlphaf(effectRegion.alpha);
+    paint.setAlpha(static_cast<int>(effectRegion.alpha * 255));
     const auto matrix = mBlurFilter->getShaderMatrix();
     paint.setShader(blurredSurface->makeImageSnapshot()->makeShader(matrix));