Merge models and dolmen into default tag

tools/gentest.ml

@@ -262,7 +262,7 @@ end = struct
                 {acc with accepted_exit_codes = [1]}
               | "timeout" ->
                 {acc with accepted_exit_codes = [142]}
-              | "models" ->
+              | "default" ->
                 {acc with filters = Some ["default"]}
               | _ -> acc
           )