Remove no longer needed buildbot PoC workers

To my knowledge they were never used and the new buildbtw[1] project is
following another path.

[1] https://gitlab.archlinux.org/archlinux/buildbtw

This reverts commit 3a555a1a (Provision workers (servers) for the buildbot POC, 2024-01-19).

tf-stage1/archlinux.tf

@@ -163,16 +163,6 @@ locals {
       domain      = "wiki"
       http3       = true
     }
-    "worker1.buildbot.pkgbuild.com" = {
-      server_type = "cx22"
-      domain      = "worker1.buildbot"
-      zone        = hetznerdns_zone.pkgbuild.id
-    }
-    "worker2.buildbot.pkgbuild.com" = {
-      server_type = "cx22"
-      domain      = "worker2.buildbot"
-      zone        = hetznerdns_zone.pkgbuild.id
-    }
   }
 
   # This creates gitlab pages verification entries.