modules/testing: increase disk size of controller

With the cinder storage node we need to increase the disk size otherwise
we ran out of disk space.

Author: hertrste

modules/testing/default.nix

@@ -54,6 +54,7 @@ in
       virtualisation = {
         cores = 4;
         memorySize = 6144;
+        diskSize = 8192;
         interfaces = {
           eth1 = {
             vlan = 1;