Show audit ui based on created date, not modified

Audits get modified for administrative reasons, not limited to marking
them as approved or migrating from an OTM1 instance.

Don't show modified date, it doesn't reflect the true history of the
object correctly. Show created date.
Right above here we are sorting and grouping audits by `updated`, not `created`.  If we display `created`, we should probably retrieve them from the DB that way as well.

Also, `updated` has an index on it (presumably for use by this method).  If we switch to retrieving by `created`, we should add an index for `created`