CI: Sync web and dev docs automatically with prod server
- [X] closes #28528

This forgets about the OVH server, and after every merge to master will synchronize the repo web and docs in the production server.

**Note** that this will delete any file in the server that is not known, except the cheat sheets, and all the docs versions in `pandas-doc`. I don't think anything else should be kept, but if there is anything else that we upload manually, please let me know. I made a backup in the server, so if we delete anything by accident with this, it can be easily restored.

CC: @TomAugspurger @jorisvandenbossche 
Looks good to me. 

But not very familiar with the server, to know whether we uploaded things manually in the past.  > delete any file in the server that is not known

Starting in what directory? `/usr/share/nginx/` or `/usr/share/nginx/pandas`? I suppose the diff answers my question: `nginx/pandas`. So this looks good.

Merge when you're ready. Yes, `nginx/pandas`. Thanks for the reviews.