CI: Update web and docs to OVH with the right structure
- [X] closes #32303

I'm uploading all the docs from the NumFOCUS server to the OVH (manually). And I'm changing the CI in this PR to upload the website and the dev docs to the server automatically.

I'll have a look and see if we can upload a new version of the docs automatically to OVH when a new GitHub release is generated. So, we never need to upload the website manually.

After merging this PR, and when we're confident this is working well, we'll have to redirect pandas.pydata.org to the OVH server. The dev docs will be available at pandas.pydata.org/pandas-docs/dev/ (and we can stop using pandas.io and dev.pandas.io).
> After merging this PR, and when we're confident this is working well, we'll have to redirect pandas.pydata.org to the OVH server. 

Did this already happen? 

And are the dev docs already available on one of the urls? https://dev.pandas.io/docs/ is not updated anymore, https://pandas.io/docs/ also not anymore since last week (when this was merged?), but https://pandas.pydata.org/pandas-docs/dev still points to the old travis-built github-hosted docs url (alendar.google.com/) > The dev docs will be available at pandas.pydata.org/pandas-docs/dev/ 

Also, could we choose pandas.pydata.org/docs/dev/ instead (a tiny bit shorter)? That url basically never existed (it was always directly redirected), so I think we don't necessarily need to keep it (it could still redirect to the new place)