MDEV-24317 Data race in LOGGER::init_error_log at sql/log.cc:1443 and in LOGGER::error_log_print at sql/log.cc:1181

don't initialize error_log_handler_list in set_handlers()
* error_log_handler_list is initialized to LOG_FILE early, in init_base()
* set_handlers always reinitializes it to LOG_FILE, so it's pointless
* after init_base() concurrent threads start using sql_log_warning,
  so following set_handlers() shouldn't modify error_log_handler_list
  without some protection