Correct validation_split_percentage argument from int (ex:5) to float (0.05)

# What does this PR do?
This PR is for fixing a bug in the run_clm.py and run_mlm.py examples in the tensorflow section. I have merely divided the value by 100 on the train_test_split test_size argument. This will make it work as intended now.




## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/master/CONTRIBUTING.md#start-contributing-pull-requests),
      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
https://github.com/huggingface/transformers/pull/11690

- [ ] Did you make sure to update the documentation with your changes? Here are the
      [documentation guidelines](https://github.com/huggingface/transformers/tree/master/docs), and
      [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/master/docs#writing-source-documentation).

- [ ] Did you write any new necessary tests?


## Who can review?

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Related People: @sgugger and @patil-suraj 

Please make sure to run `make style` on your branch to fix the formatting issues.<|||||>Thanks for fixing!<|||||>Thanks for kind help with the formatting 