refactor: Refactoring to match the rest of terraform-aws-modules (#1583)

examples/launch_templates_with_managed_node_groups/variables.tf

@@ -1,15 +1,6 @@
-variable "region" {
-  default = "eu-central-1"
-}
-
 variable "instance_type" {
+  description = "Instance type"
   # Smallest recommended, where ~1.1Gb of 2Gb memory is available for the Kubernetes pods after ‘warming up’ Docker, Kubelet, and OS
-  default = "t3.small"
   type    = string
-}
-
-variable "kms_key_arn" {
-  default     = ""
-  description = "KMS key ARN to use if you want to encrypt EKS node root volumes"
-  type        = string
+  default = "t3.small"
 }