Revert "Dsiable CPU/GPU measurement on BackdropFilter test (#41736)" (#41780)

This reverts c9d920f3 so that we can attempt to fix the build. The build dashboard clearly shows that things started failing at this change, although it's not totally clear that it is the cause: tests succeed locally.

If it doesn't fix things we can re-land this.

dev/devicelab/bin/tasks/backdrop_filter_perf_ios__timeline_summary.dart

@@ -10,5 +10,5 @@ import 'package:flutter_devicelab/framework/framework.dart';
 
 Future<void> main() async {
   deviceOperatingSystem = DeviceOperatingSystem.ios;
-  await task(createBackdropFilterPerfTest());
+  await task(createBackdropFilterPerfTest(needsMeasureCpuGpu: true));
 }