Determine if updated can ever be false when a registration record is found (but not changed)

[dlongley]

See: https://github.com/digitalbazaar/bedrock-tokenization/blob/v21.1.0/lib/documents.js#L320

From testing, it appears that updated will always be set to true whether or not the record in the database changed based on lastErrorObject.n being set to 1 (this is how updated is implemented internally). If updated is always true, we can simplify at least the comment exposition that follows after the above link in the function (and remove the FIXME) -- it may not change the code.