Stab PG's pg_total_relation_size() (#6659)

Author: marsaly79

ydb/library/yql/parser/pg_wrapper/postgresql/src/backend/utils/adt/dbsize.c

@@ -546,6 +546,12 @@ calculate_total_relation_size(Relation rel)
 
 Datum
 pg_total_relation_size(PG_FUNCTION_ARGS)
+{
+    return (Datum)0;
+}
+
+Datum
+pg_total_relation_size_original(PG_FUNCTION_ARGS)
 {
 	Oid			relOid = PG_GETARG_OID(0);
 	Relation	rel;