Fix transparency issue on MacOS (#4358)

Signed-off-by: AMZN-alexpete <26804013+AMZN-alexpete@users.noreply.github.com>

Code/Tools/ProjectManager/Source/ProjectsScreen.cpp

@@ -358,8 +358,9 @@ namespace O3DE::ProjectManager
         painter.drawPixmap(backgroundRect, m_background);
 
         // Draw a semi-transparent overlay to darken down the colors.
-        painter.setCompositionMode (QPainter::CompositionMode_DestinationIn);
-        const float overlayTransparency = 0.7f;
+        // Use SourceOver, DestinationIn will make background transparent on Mac
+        painter.setCompositionMode (QPainter::CompositionMode_SourceOver);
+        const float overlayTransparency = 0.3f;
         painter.fillRect(backgroundRect, QColor(0, 0, 0, static_cast<int>(255.0f * overlayTransparency)));
     }