fix: Ensure a default ip_family value is provided to guarantee a CNI policy is attached to nodes (#2967)

modules/self-managed-node-group/variables.tf

@@ -549,7 +549,7 @@ variable "create_iam_instance_profile" {
 variable "cluster_ip_family" {
   description = "The IP family used to assign Kubernetes pod and service addresses. Valid values are `ipv4` (default) and `ipv6`"
   type        = string
-  default     = null
+  default     = "ipv4"
 }
 
 variable "iam_instance_profile_arn" {