Migrating git server to a new host and setup

[Baptiste Jonglez]

Hi,

Paul and me started working on improving reliability of the git server
setup, by deploying a new server with:

- newer OS (Debian 13 vs Debian 11)
- standard Ansible setup
- use cgit instead of gitweb as webinterface
- disable costly web requests (blame, magic commit lookup)
- allocate more hardware resources (pending)

The new setup is accessible here: https://git.staging.openwrt.org

We tried to keep compatibility with existing gitweb URLs through redirects
(except the magic git.openwrt.org/<commit_hash> since it iterates on all
repositories, which is quite costly).

Please test and report any issues.

We plan to migrate the main git.openwrt.org DNS to the new server this
Wednesday evening (UTC).  If we notice major issues, we may postpone it.

Baptiste