CI: Remove docs build from pipelines
- [X] closes #29472

At the moment we're building the web and the docs from both Actions and Pipelines. While is still under discussion where things should be hosted, it's probably worth to just build on Actions for now, and publish from there to both the OVH cloud, and to GitHub pages.

**This needs the GitHub pages ssh key to be added to the secrets of this repo with name "github_pages_ssh_key".*** Can someone with permissions please add it? Or if we already got it with a different name, please let me know the name.

> Can someone with permissions please add it?

cc @TomAugspurger  I'm not sure what the value of the key is. Perhaps @jorisvandenbossche has it? Sent them via email. Thanks @datapythonista. Added to the pandas-dev/pandas github repo's secrets with the name `github_pages_ssh_key`. Cool, this should be ready then. As a follow up, I'll synchronize the website and the dev docs in the rackspace server in the GitHub Actions build. I just noticed https://github.com/ammaraskar/sphinx-action (a github action to build sphinx docs and puts errors inline), might be interesting (but didn't really look at it) All green after rebasing, merging.