Try to fix cloud_storage error for Elasticsearch version prior 7.9

Author: dm3ch

main.tf

@@ -158,8 +158,11 @@ resource "aws_elasticsearch_domain" "default" {
       }
     }
 
-    cold_storage_options {
+    dynamic "cold_storage_options" {
+      for_each = var.cold_storage_enabled ? [true] : []
+      content {
       enabled = var.cold_storage_enabled
+      }
     }
   }