run_glue_no_trainer: datasets -> raw_datasets
# What does this PR do?

Use the correct variable (raw_datasets) instead of the module (datasets)
where appropriate. The script will otherwise fail with "module object is not subscriptable".

Fixes # (issue)

## Before submitting
- [ ] This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
- [ ] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/master/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/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?
@sgugger 
Creating a quick PR now to alert to some issues I'm encountering, will backfill with proper GitHub issues after I knock off from work.

Other issues:
- [ ] If task_name is `None`, `metrics` is undefined, and will throw `... metrics used before assignment`