Fix self-push CI report path in cat
# What does this PR do?

`self-push.yml` has lines like

```
run: cat reports/tests_torch_gpu_failures_short.txt
```
which should be 
```
run: cat reports/tests_torch_gpu/failures_short.txt
```

Currently, we get errors like
```
cat: reports/tests_torch_multi_gpu_failures_short.txt: No such file or directory
Error: Process completed with exit code 1.
```

(see for example [this job](https://github.com/huggingface/transformers/runs/6307735900?check_suite_focus=true)).
_The documentation is not available anymore as the PR was closed or merged._<|||||>> If this change is needed, it should also be done in the other GitHub action files, 

The other occurrences are in `self-nightly-scheduled.yml"`. ~~I can update it too.~~ **Done**

> and also in the report part of the job? Not sure if they will push properly nested files in subdirectories.

I guess you are talking about files like `notification_service_deprecated.py` and `notification_service.py`. They are not using `failures_short.txt`. 

Note that:
 - this PR doesn't change any artifact directory location
 - `notification_service_deprecated.py` does have issues with the report.
   - For example, `"run_all_tests_tf_gpu_test_reports/[X].txt"` should be `run_all_tests_tf_gpu_test_reports/tests_torch_gpu/[X].txt`
     - (if we don't change the artifact directory in `self-push.yml`)  
   - I am still on the task of the self-push report format, which might still take some time.
     - But think I can already fix a few small things in the meantime.