fix(security_options): interbal DB and role ARN conditional

master_db user and pass works only if internal DB is enabled
master_user_arn works only if internal DB is disable

So, a conditional is needed to avoid terraform to fail on apply

data.tf

@@ -4,7 +4,7 @@ data "aws_caller_identity" "current" {}
 
 data "aws_route53_zone" "opensearch" {
   name = var.cluster_domain
-  
+
   private_zone = var.cluster_domain_private
 }
 

main.tf

@@ -56,9 +56,9 @@ resource "aws_elasticsearch_domain" "opensearch" {
       internal_user_database_enabled = var.advanced_security_options_internal_user_database_enabled
 
       master_user_options {
-        master_user_arn = (var.master_user_arn != "") ? var.master_user_arn : data.aws_caller_identity.current.arn
-        master_user_name     = var.advanced_security_options_master_user_name
-        master_user_password = var.advanced_security_options_master_user_password
+        master_user_arn      = var.advanced_security_options_internal_user_database_enabled ? null : (var.master_user_arn != "" ? var.master_user_arn : data.aws_caller_identity.current.arn)
+        master_user_name     = var.advanced_security_options_internal_user_database_enabled ? var.advanced_security_options_master_user_name : null
+        master_user_password = var.advanced_security_options_internal_user_database_enabled ? var.advanced_security_options_master_user_password : null
       }
     }
   }