chore(e2e): Added the option to make member server kerberos only (#5997)

* chore(e2e): Added the option to make member server kerberos only

enos/modules/aws_rdp_domain_controller/variables.tf

@@ -46,10 +46,4 @@ variable "active_directory_domain" {
   type        = string
   description = "The name of the Active Directory domain to be created on the Windows Domain Controller."
   default     = "mydomain.com"
-}
-
-variable "active_directory_netbios_name" {
-  type        = string
-  description = "Ostensibly the short-hand for the name of the domain."
-  default     = "mydomain"
-}
+}