Scale up debuginfod to CPX11

We've been seeing CPU spikes that a single vCPU can't handle, resulting
in alerts about high CPU usage. Let's try two cores to see how they do.

tf-stage1/archlinux.tf

@@ -77,7 +77,7 @@ locals {
       domain      = "dashboards"
     }
     "debuginfod.archlinux.org" = {
-      server_type = "cx11"
+      server_type = "cpx11"
       domain      = "debuginfod"
     }
     "gitlab.archlinux.org" = {