Update the vocabulary size for the Stanford Sentiment problem.
Update the vocabulary size for the Stanford Sentiment problem.

PiperOrigin-RevId: 204163583

tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,tensorflow/tensor2tensor,vthorsteinsson/tensor2tensor,vthorsteinsson/tensor2tensor