[Openstack] Add security groups not managed by terraform (#6865)

* add custom sec groups

* make sure groups are applied only when created

* fix spacing

contrib/terraform/openstack/modules/compute/variables.tf

@@ -127,3 +127,11 @@ variable "use_access_ip" {}
 variable "use_server_groups" {
   type = bool
 }
+
+variable "extra_sec_groups" {
+  type = bool
+}
+
+variable "extra_sec_groups_name" {
+  type = string
+}