Revert "Small tidy up: Removed unused leftover variables. The variable layer.trainable_weights has all we need."

This reverts commit 7b7fe53.

Author: benkli01

tensorflow_model_optimization/python/core/clustering/keras/cluster_wrapper.py

@@ -326,11 +326,11 @@ def trainable(self, value):
 
   @property
   def trainable_weights(self):
-    return self.layer.trainable_weights
+    return self.layer.trainable_weights + self._trainable_weights
 
   @property
   def non_trainable_weights(self):
-    return self.layer.non_trainable_weights
+    return self.layer.non_trainable_weights + self._non_trainable_weights
 
   @property
   def updates(self):