fix: add default value has_mc_flag field (#3710)

Author: BorysTheDev

src/server/rdb_load.cc

@@ -1905,7 +1905,7 @@ struct RdbLoader::ObjSettings {
   bool has_expired = false;
 
   bool is_sticky = false;
-  bool has_mc_flags;
+  bool has_mc_flags = false;
 
   void Reset() {
     expiretime = 0;