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

examples/bottlerocket/variables.tf

@@ -1,17 +0,0 @@
-variable "k8s_version" {
-  description = "k8s cluster version"
-  default     = "1.20"
-  type        = string
-}
-
-variable "enable_admin_container" {
-  description = "Enable/disable admin container"
-  default     = false
-  type        = bool
-}
-
-variable "enable_control_container" {
-  description = "Enable/disable control container"
-  default     = true
-  type        = bool
-}