run the test longer time (#64185)

dev/benchmarks/macrobenchmarks/test/multi_widget_construction_perf_e2e.dart

@@ -11,7 +11,7 @@ void main() {
     'multi_widget_construction_perf',
     kMultiWidgetConstructionRouteName,
     pageDelay: const Duration(seconds: 1),
-    duration: const Duration(seconds: 10),
-    timeout: const Duration(seconds: 45),
+    duration: const Duration(seconds: 20),
+    timeout: const Duration(seconds: 60),
   );
 }

dev/benchmarks/macrobenchmarks/test_driver/multi_widget_construction_perf_test.dart

@@ -11,7 +11,7 @@ void main() {
     'multi_widget_construction_perf',
     kMultiWidgetConstructionRouteName,
     pageDelay: const Duration(seconds: 1),
-    duration: const Duration(seconds: 10),
-    timeout: const Duration(seconds: 45),
+    duration: const Duration(seconds: 20),
+    timeout: const Duration(seconds: 60),
   );
 }

dev/devicelab/manifest.yaml

@@ -170,6 +170,7 @@ tasks:
       Measures the runtime performance of constructing and destructing widgets on Android.
     stage: devicelab
     required_agent_capabilities: ["linux/android"]
+    flaky: true
 
   multi_widget_construction_perf__e2e_summary:
     description: >