[TF-Agents] ReverbReplayBuffer: Fix bug in dataset buffer size when batch_size > 32.
[TF-Agents] ReverbReplayBuffer: Fix bug in dataset buffer size when batch_size > 32.

Updates Reverb RB settings now that we sometimes have cycle_length != batch_size.

This speeds up some tf.data pipelines up to 2x.

PiperOrigin-RevId: 321387885
Change-Id: I3e9c7e1dfb5230c9da072d66f8348772c30cd80e

tensorflow/agents,tensorflow/agents