Roll engine to 50c2e69da with goldens fix (#23016)

Goldens updated due to Skia AA changes. We previously also made a mistake by having a golden test run on MacOS.

git log 3ffa36295234..50c2e69da --no-merges --oneline
50c2e69da Roll src/third_party/skia 1b62fad4b188..b27a9cf2f4a8 (1 commits) (flutter/engine#6514)
8757bf2a1 Roll src/third_party/skia 05caa69a3f5a..1b62fad4b188 (2 commits) (flutter/engine#6513)
c2fd10ad1 Roll src/third_party/skia 2a138544646d..05caa69a3f5a (1 commits) (flutter/engine#6512)

bin/internal/engine.version

-3ffa362952340ddee3febb0efa9599091c0d2fc6
+50c2e69daff4e207c54e463d2304139985c7511c

bin/internal/goldens.version

-b84f87078729d0af8380fd9826091d8bafe6fcc7
+fcb6a6cad08bd4a7d5c0157b9f83acadfa9be7e3

packages/flutter/test/cupertino/segmented_control_test.dart

@@ -1314,7 +1314,7 @@ void main() {
       find.byType(RepaintBoundary),
       matchesGoldenFile('segmented_control_test.0.0.png'),
     );
-  }, skip: !Platform.isMacOS);
+  }, skip: !Platform.isLinux);
 
   testWidgets('Golden Test Pressed State', (WidgetTester tester) async {
     final Map<int, Widget> children = <int, Widget>{};
@@ -1352,5 +1352,5 @@ void main() {
       find.byType(RepaintBoundary),
       matchesGoldenFile('segmented_control_test.1.0.png'),
     );
-  }, skip: !Platform.isMacOS);
+  }, skip: !Platform.isLinux);
 }