Stop monitoring status.archlinux.org

We aren't interested if status.archlinux.org is down as it's not part of
our own infra.

roles/prometheus/defaults/main.yml

@@ -34,7 +34,6 @@ blackbox_targets:
   - https://reproducible.archlinux.org
   - https://security.archlinux.org
   - https://sources.archlinux.org
-  - https://status.archlinux.org
   - https://whatcanwedofor.archlinux.org
   - https://wiki.archlinux.org
   - https://www.archlinux.org