Minor It has no interest to update dc:modified when adding/updating the thumbnail.
It also makes some Drive functional tests fail randomly because the remote scan gets modification dates from the server that might be later updated by the asynchronous thumbnail listener followed by the DublinCoreListener.
Though it should not be a problem during the "real" Drive execution because it only relies on the audit, and NXP-11959 prevents from logging thumbnail updates in it.
