use small volumes in arcus/CI environment

Author: sjpb

environments/arcus/terraform/main.tf

@@ -51,4 +51,7 @@ module "cluster" {
     create_nodes = var.create_nodes
 
     environment_root = var.environment_root
+    # Can reduce volume size a lot for short-lived CI clusters:
+    state_volume_size = 10
+    home_volume_size = 20
 }