Revert changes to SAC v2 trainer.
Revert changes to SAC v2 trainer.

Example should not differ in how summaries are built with respect to other examples.
Reward normalization changes did not follow latest SAC published results.

PiperOrigin-RevId: 288929954
Change-Id: I16b95208d42dc1bcc4ff17f1bd9156bd93bf8048

tensorflow/agents,tensorflow/agents