Dispose routes in navigator when throwing exception (flutter#134596)

fixes: flutter#133695
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Author: hannah-hyj

packages/flutter/lib/src/widgets/navigator.dart

@@ -2792,6 +2792,9 @@ class Navigator extends StatefulWidget {
           );
           return true;
         }());
+        for (final Route<dynamic>? route in result) {
+          route?.dispose();
+        }
         result.clear();
       }
     } else if (initialRouteName != Navigator.defaultRouteName) {

packages/flutter/test/material/app_test.dart

@@ -334,15 +334,7 @@ void main() {
       expect(find.text('route "/a/b"'), findsNothing);
       expect(find.text('route "/b"'), findsNothing);
     }
-  },
-  // TODO(polina-c): remove after fixing
-  // https://github.com/flutter/flutter/issues/133695
-  leakTrackingTestConfig: const LeakTrackingTestConfig(
-    notDisposedAllowList: <String, int?> {
-      'ValueNotifier<String?>': 3,
-      'MaterialPageRoute<dynamic>': 3,
-    },
-  ));
+  });
 
   testWidgetsWithLeakTracking('Make sure initialRoute is only used the first time', (WidgetTester tester) async {
     final Map<String, WidgetBuilder> routes = <String, WidgetBuilder>{