ChangeJson: Restore async reviewed bit loading

loadReviewed was supposed to be cleverly creating ResultSets but not
iterating over them, which may kick off an asynchronous query in some
implementations. Unfortunately, when converting ChangeMessages to
notedb, this was replaced by eagerly memoizing the results into a
list. Restore the faster behavior by not sorting the list that comes
out of ChangeMessagesUtil and leaving it as a ResultSet.

Change-Id: I8c6e5e7a16932c24f9ddec4d0b5b7438636bd375
2 files changed