workflows: no error if nothing harvested

• Changes the logic of workflows_reviews to not cause an error if nothing was harvested as this can be a natural event.

• Changes the wording to report more positively.

Reviewed-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>