MINOR: cli: use srv_drop() when server was created using new_server()

Now that new_server() is becoming more and more complex, we need to
take care that servers created using new_server() must be released
using the corresponding release function srv_drop() which takes care
of properly de-initing the server and its members.

src/cli.c

@@ -3737,11 +3737,8 @@ int mworker_cli_attach_server(char **errmsg)
 
 error:
 
-	list_for_each_entry(child, &proc_list, list) {
-		free((char *)child->srv->conf.file); /* cast because of const char *  */
-		free(child->srv->id);
-		srv_free(&child->srv);
-	}
+	list_for_each_entry(child, &proc_list, list)
+		srv_drop(child->srv);
 	free(msg);
 
 	return -1;

src/server.c

@@ -3434,7 +3434,7 @@ static int _srv_parse_tmpl_init(struct server *srv, struct proxy *px)
 		free_check(&newsrv->check);
 		MT_LIST_DELETE(&newsrv->global_list);
 	}
-	srv_free(&newsrv);
+	srv_drop(newsrv);
 	return i - srv->tmpl_info.nb_low;
 }