Fixes tags for DGI Reservation

Third indexer not reserved, since it's nonexistent.

prod/aws-us-gov/mdr-prod-dgi/160-splunk-indexer-cluster/terragrunt.hcl

@@ -46,9 +46,9 @@ inputs = {
       Reservation_Expiration = "2023-04-09"
     },
     {
-      Reserved               = true
-      Reserved_Type          = "i3en.3xlarge"
-      Reservation_Expiration = "2023-04-09"
+      Reserved               = false
+      Reserved_Type          = ""
+      Reservation_Expiration = ""
     }
   ]
   prefix          = local.account_vars.locals.splunk_prefix