[CIs] Better reports everywhere
Continuing the work in https://github.com/huggingface/transformers/pull/8110 and https://github.com/huggingface/transformers/pull/8163 this PR does the following:

* [x] rename `pytest --make_reports` to `pytest --make-reports` for consistency with the rest of `pytest` opts that don't use `_`
* [x] move the `--make_reports` opt adding to a shared location and load it only once to avoid `pytest` failure 
   - some pytest plugins like `pytest-instafail` load `tests/conftest.py` even when running `examples`
   - now we can run tests from both test suites at once
* [x] rename `reports/report_foo` to `reports/foo` - avoid repetition
* [x] install `--make_reports` in all CIs: circleci and github actions 
* [x] make the reports available via artifacts
* [x] always cat short failure reports for github actions in its own "tab" since getting to artifacts there is a cumbersome process. I'm not sure this is needed in circleci jobs since each report in artifacts is available in 2 clicks, so I left the `cat *failures_short.txt` out on CircleCI jobs.
* [x] fixed a few issues in the github actions job configuration

@sgugger, @LysandreJik, @sshleifer 

And and update on proposing this multiple report files feature to be a core feature in pytest https://github.com/pytest-dev/pytest/issues/7972 - one of the developers vetoed it, so I guess it will remain just here for now. It makes no sense for this not to be a core feature of pytest, as we are just splitting the huge mess of everything being dumped to the terminal to just one file per report, but there was no invitation to discuss that - just NO. If someone wants to make it into a pytest plugin it'd surely be useful to others.<|||||>> I saw the discussion (or lack thereof) on pytest. Their loss! We don't mind having the post-processing in transformers.

Eventually we will either have to port it to pytest hooks or keep up with the pytest API changes, since currently the code uses `pytest` internals and could break should they change those. It's just so much simpler doing that than reinventing the wheel.