Fix confusing `transformers` installation in CI
# What does this PR do?

As mentioned in [this comment](https://github.com/huggingface/transformers/pull/23277#issuecomment-1544080975), the `transformers` in CI runs is not the same one installed during docker image build.

Furthermore, for past CI, we didn't update the docker image daily (there is no need to update the fixed 3rd-packages environment), but the `transformers` code is the latest one being test against. We get 
```bash
E   ImportError: cannot import name 'HfDoctestModule' from 'transformers.testing_utils'
```
as the `transformers` is the one during docker image build (months ago) which has no `HfDoctestModule` at the time.

To avoid and fix all such super confusing failures in the future, it's better to install the `transformers` again in the edit mode in the workflow files.

I don't change the daily CI workflow file yet in this PR -  I would wait this PR showing the change actually fix issues.
_The documentation is not available anymore as the PR was closed or merged._<|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_23465). All of your documentation changes will be reflected on that endpoint.