Remove non-breaking spaces
# What does this PR do?

This PR removes non-breaking spaces in various places in the codebase. The first commit was from when I first found the problem over a year ago, and the second commit fixes all other non-breaking spaces in the repository as of now.

I'm not sure of a good check to prevent this going forward, but it at least fixes the problem as it exists now.

## Before submitting
- [x] 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/main/CONTRIBUTING.md#start-contributing-pull-requests), Pull Request section?
- [ ] 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.
- [ ] Did you make sure to update the documentation with your changes? Here are the [documentation guidelines](https://github.com/huggingface/transformers/tree/main/docs), and [here are tips on formatting docstrings](https://github.com/huggingface/transformers/tree/main/docs#writing-source-documentation).
- [ ] Did you write any new necessary tests?

## Who can review?

Library:

- trainer: @sgugger

Documentation: @sgugger and @stevhliu
_The documentation is not available anymore as the PR was closed or merged._