fix(db): delete duplicated callback

[mattisonchao]

Motivation

In the old logic, there's the wrong usage for iteration is as follow:

for it.Next() {
	err := updateOperationCallback.OnDelete(batch, it.Key())
	if err != nil {
		return errors.Wrap(multierr.Combine(err, it.Close()), "oxia db: failed to delete range")
	}
}

After pr #544, we already added a deleteRange callback. Therefore, we can delete this wrong logic directly.