We don't actually need this since the only reason it exists is to pass
the owning class name down to the `handler`. This removes a level of
indirection and an unnecessary accessor on db_config. db_config
shouldn't have to know what class owns it, so we can just remove this
and pass it to the handler.

The Symbol case is needed to preserve current behavior. This doesn't
need a changelog because it's changing un-released behavior.

Co-authored-by: John Crepezzi <john.crepezzi@gmail.com>