Mark integration_ui_test_test_macos unflaky (#160999)

This should have been marked unflaky when
flutter/flutter#152212 was closed.

Author: jmagman

.ci.yaml

@@ -4210,7 +4210,6 @@ targets:
       task_name: hello_world_macos__compile
 
   - name: Mac integration_ui_test_test_macos
-    bringup: true # Flaky https://github.com/flutter/flutter/issues/152212
     recipe: devicelab/devicelab_drone
     presubmit: false
     timeout: 60