[FEAT MERGE] Support external table

Co-authored-by: jingtaoye35 <1255153887@qq.com>

src/share/stat/ob_dbms_stats_utils.cpp

@@ -210,7 +210,7 @@ int ObDbmsStatsUtils::check_is_stat_table(share::schema::ObSchemaGetterGuard &sc
   } else if (OB_ISNULL(table_schema)) {
     //do nothing
   } else {//check user table
-    is_valid = table_schema->is_user_table();
+    is_valid = table_schema->is_user_table() || table_schema->is_external_table();
   }
   return ret;
 }