Cherrypick ImageAugmetation related change to R2.9 (#16454)

* Enable the keras dtensor API in OSS.

PiperOrigin-RevId: 438858608

* Switching learning/brain dependency to OSS compatible test_util

This is one test file failing, due to the monkey patching happens in the dtensor.init(), and I will need to dig more about the root cause (probably due to patching tf.Variable with DVariable, and cause logic difference for instance type checking.)

PiperOrigin-RevId: 439676157

* Update the docstring for keras.dtensor components.

1. Add docstring for LayoutMap.
2. Hide certain methods for keras.dtensor.optimizers.

PiperOrigin-RevId: 442651549

* add no-op label augmentation to RandomContrast

PiperOrigin-RevId: 439938098

* Add augment_label to RandomBrightness

PiperOrigin-RevId: 443122383

* Create augment_label method:
```
  def augment_label(self, label, transformation=None):
    return label
```
on remaining image augmentation layers

PiperOrigin-RevId: 443446864

* Revert "Create augment_label method:"

This reverts commit 1694cb4.

Co-authored-by: Luke Wood <lukewood@google.com>

Author: qlzh727

keras/layers/preprocessing/image_preprocessing.py

@@ -1527,6 +1527,9 @@ def __init__(self, factor, value_range=(0, 255), seed=None, **kwargs):
   def augment_image(self, image, transformation=None):
     return self._brightness_adjust(image, transformation['rgb_delta'])
 
+  def augment_label(self, label, transformation=None):
+    return label
+
   def get_random_transformation(self,
                                 image=None,
                                 label=None,