DistilBertTokenizer defaults to tokenize_chinese_chars=True
## 🐛 Bug

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Model I am using DistilBert:
Language I am using the model on English

The problem arise when using:
* [ ] the official example [run_tf_ner.py](https://github.com/huggingface/transformers/blob/master/examples/run_tf_ner.py)  scripts

The tasks I am working on is:
* [ ] an official GLUE/SQUaD task: SST-2

## To Reproduce
Steps to reproduce the behavior:

1. run run_tf_ner.py

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## Expected behavior
I am expecting DistilBertTokenizer to have a tokenize_chinese_chars=False but because it extends BertTokenizer, the default is set to be tokenize_chinese_chars=True

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## Environment

* OS: Ubuntu 18.04
* Python version: 3.7.6

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