Previously, we called TimeUtil.nowTs() both in the ReviewDb and in the
NoteDb code. This resulted in different timestamps being used for the
audit log entries of ReviewDb and NoteDb. Depending on various factors,
the difference between those two timestamps could easily be more than
just a second.
In order to ensure comparability of the audit log of ReviewDb with the
one of NoteDb, we now use the same timestamp for both.
This breaks the extension point GroupMemberAuditListener but has the
benefit that all receivers of audit events will record the same
timestamps from now on.
To avoid confusion, the field 'createdOn' for group creations is
superseded by the field 'updatedOn'. Furthermore, not explicitly setting
the timestamp for group creations is supported now. Except for tests and
migrations, the automatically picked timestamp is sufficient.
Change-Id: I55b8d10eb978ae1c34ee809aff45a9a4b3c8e255
6e2a18402c