message: Have `model_to_estimator` make a V2 Estimator if TF2 is enabled.
diff: @@ -103,7 +103,8 @@ def model_to_estimator(
  custom_objects=custom_objects,
  model_dir=model_dir,
  config=config,
  - checkpoint_format=checkpoint_format)
  + checkpoint_format=checkpoint_format,
  + use_v2_estimator=False)
  @keras_export('keras.estimator.model_to_estimator', v1=[])
  @@ -161,7 +162,6 @@ def model_to_estimator_v2(
  custom_objects=custom_objects,
  model_dir=model_dir,
  config=config,
  - checkpoint_format=checkpoint_format)
  + checkpoint_format=checkpoint_format,
  + use_v2_estimator=True)
  # LINT.ThenChange(//tensorflow_estimator/python/estimator/keras.py)
  -
  -
  