Skip flaking scheduler test (#166471)

Noticed this is a recurring flake in 
-
https://github.com/flutter/flutter/issues/165470#issuecomment-2771927113
-
https://github.com/flutter/flutter/issues/165479#issuecomment-2771927163

Filed https://github.com/flutter/flutter/issues/166470 for follow up
investigation.

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packages/flutter/test/scheduler/scheduler_test.dart

@@ -322,7 +322,7 @@ void main() {
     // callback that reschedules the engine frame.
     warmUpDrawFrame();
     expect(scheduler.hasScheduledFrame, isTrue);
-  });
+  }, skip: true); // Flaky, follow up in https://github.com/flutter/flutter/issues/166470
 
   test('Can schedule futures to completion', () async {
     bool isCompleted = false;