Run devicelab test xcarchive export as development method (#97615)

dev/devicelab/bin/tasks/ios_content_validation_test.dart

@@ -19,6 +19,8 @@ Future<void> main() async {
         await inDirectory(flutterProject.rootPath, () async {
           await flutter('build', options: <String>[
             'xcarchive',
+            '--export-method',
+            'development',
           ]);
         });