upcloud: v5.6.0 and better server groups (#11311)

contrib/terraform/upcloud/variables.tf

@@ -32,6 +32,7 @@ variable "machines" {
     cpu       = string
     mem       = string
     disk_size = number
+    server_group : string
     additional_disks = map(object({
       size = number
       tier = string
@@ -142,7 +143,6 @@ variable "server_groups" {
 
   type = map(object({
     anti_affinity_policy = string
-    servers              = list(string)
   }))
 
   default = {}