Fix scroll key for bad scroll benchmark (#110440)

dev/benchmarks/complex_layout/lib/src/app.dart

@@ -104,7 +104,10 @@ class ComplexLayoutState extends State<ComplexLayout> {
       },
     );
     if (widget.badScroll) {
-      body = ListView(children: <Widget>[body]);
+      body = ListView(
+        key: const Key('complex-scroll-bad'),
+        children: <Widget>[body],
+      );
     }
 
     return Scaffold(

dev/benchmarks/complex_layout/test_driver/scroll_perf_bad_test.dart

@@ -53,7 +53,7 @@ void main() {
     }
 
     test('complex_layout_scroll_perf', () async {
-      await testScrollPerf('complex-scroll', 'complex_layout_scroll_perf');
+      await testScrollPerf('complex-scroll-bad', 'complex_layout_scroll_perf');
     }, timeout: Timeout.none);
   });
 }