Prevent writing grid state to gs://k8s-testgrid, allow a subdir
Prevent writing grid state to gs://k8s-testgrid, allow a subdir

GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid,GoogleCloudPlatform/testgrid