Update some of the mirrors in the squid config.
Review Request #14877 — Created March 5, 2026 and submitted — Latest diff uploaded
The xenyth mirror doesn't have modern CentOS, Rocky Linux, or Arch
packages (though it is current for Fedora). This updates the squid
config to point to a different mirror for those.
Ran install tests and didn't get 404s with newer versions of these
distros.