Marks Windows_android channels_integration_test_win to be flaky (flutter#134637)

<!-- meta-tags: To be used by the automation script only, DO NOT MODIFY.
{
  "name": "Windows_android channels_integration_test_win"
}
-->
Issue link: flutter#134636

Author: fluttergithubbot

.ci.yaml

@@ -5101,6 +5101,7 @@ targets:
       task_name: basic_material_app_win__compile
 
   - name: Windows_android channels_integration_test_win
+    bringup: true # Flaky https://github.com/flutter/flutter/issues/134636
     recipe: devicelab/devicelab_drone
     presubmit: false
     timeout: 60