message: use dataset_ops instead of tf import
diff: @@ -700,7 +700,7 @@ class DataServiceOpsTest(data_service_test_base.TestBase,
  ds2 = dataset_ops.Dataset.from_tensor_slices(numbers)
  ds2 = self.make_distributed_dataset(ds2, cluster_2)
  - ds3 = tf.data.Dataset.zip((ds1, ds2))
  + ds3 = dataset_ops.Dataset.zip((ds1, ds2))
  ds3 = self.make_distributed_dataset(
  ds3, cluster_3, processing_mode="parallel_epochs")
  