- Closes PR #2839
- Usage of `Column_definition_fix_attributes()` suggested by Alexandar
  Barkov - thanks bar, that is better than hook in server code
  (reverted 22f3ebe4)
  - This method is called after parsing the data type:
    * in `CREATE/ALTER TABLE`
    * in SP: return data type, parameter data type, variable data type
  - We want to disallow all these use cases of MYSQL_JSON.

- Reviewer: bar@mariadb.com
            cvicentiu@mariadb.org