Temporarily skip benchmark tests (#9676)

packages/devtools_app/benchmark/devtools_benchmarks_test.dart

diff --git a/packages/devtools_app/benchmark/devtools_benchmarks_test.dart b/packages/devtools_app/benchmark/devtools_benchmarks_test.dart
index 31e271c..c8bf4b8 100644
--- a/packages/devtools_app/benchmark/devtools_benchmarks_test.dart
+++ b/packages/devtools_app/benchmark/devtools_benchmarks_test.dart
@@ -44,6 +44,8 @@
       },
       timeout: const Timeout(Duration(minutes: 15)),
       retry: 0,
+      // TODO(elliette): Re-enable once flakiness is addressed.
+      skip: 'https://github.com/flutter/devtools/issues/9674',
     );
   }
 }