set max examples to use for subword vocab for wsj_parsing problem.
set max examples to use for subword vocab for wsj_parsing problem.

PiperOrigin-RevId: 209666801

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