disable Impeller on external texture test. (#149292)

This is failing with Impeller:
https://ci.chromium.org/ui/p/flutter/builders/try/Linux_android_emu%20external_textures_integration_test/1414/overview

Needs investigation.

Author: jonahwilliams

dev/devicelab/bin/tasks/external_textures_integration_test.dart

@@ -8,5 +8,5 @@ import 'package:flutter_devicelab/tasks/integration_tests.dart';
 
 Future<void> main() async {
   deviceOperatingSystem = DeviceOperatingSystem.android;
-  await task(createExternalTexturesFrameRateIntegrationTest());
+  await task(createExternalTexturesFrameRateIntegrationTest(extraOptions: <String>['--no-enable-impeller']));
 }

dev/devicelab/lib/tasks/integration_tests.dart

@@ -40,10 +40,11 @@ TaskFunction createIntegrationTestFlavorsTest({Map<String, String>? environment}
   ).call;
 }
 
-TaskFunction createExternalTexturesFrameRateIntegrationTest() {
+TaskFunction createExternalTexturesFrameRateIntegrationTest({ List<String> extraOptions = const <String>[] }) {
   return DriverTest(
     '${flutterDirectory.path}/dev/integration_tests/external_textures',
     'lib/frame_rate_main.dart',
+    extraOptions: extraOptions,
   ).call;
 }