Adding a new statement into scripts/sys_schema/before_setup.sql:

  ALTER DATABASE sys CHARACTER SET utf8mb3 COLLATE utf8mb3_general_ci;

to fix db.opt in case:
- the database `sys` was altered to unexpected CHARACTER SET or COLLATE values
- or db.opt was erroneously removed

to make sure that sys objects are always recreated using utf8mb3_general_ci.