Fix REST catalog config merge precedence

Author: plusplusjiajia

src/iceberg/catalog/rest/rest_catalog.cc

@@ -117,7 +117,7 @@ Result<std::shared_ptr<RestCatalog>> RestCatalog::Make(
   ICEBERG_ASSIGN_OR_RAISE(auto server_config, FetchServerConfig(*paths, config));
 
   std::unique_ptr<RestCatalogProperties> final_config = RestCatalogProperties::FromMap(
-      MergeConfigs(server_config.overrides, config.configs(), server_config.defaults));
+      MergeConfigs(server_config.defaults, config.configs(), server_config.overrides));
 
   std::unordered_set<Endpoint> endpoints;
   if (!server_config.endpoints.empty()) {