Remove archbuild role from sgp

It should not be used as a build server anymore:

https://wiki.archlinux.org/index.php/DeveloperWiki:DevopsMeetings/2019-11-28#Actionable_5

playbooks/sgp.yml

@@ -15,7 +15,6 @@
     - { role: syncrepo, tags: ['nginx'] }
     - { role: arch32_mirror, tags: ['nginx'] }
     - { role: sogrep }
-    - { role: archbuild }
     - { role: archweb, archweb_site: false, archweb_services: false, archweb_mirrorcheck: true }
     - { role: crond }
     - { role: zabbix-agent, tags: ["zabbix"] }