uploader: refactoring of workflow definition

• Refactors the "insert" workflow definitions to conform with the standard pattern of workflows. This will also avoid the current issue that the workflows registry has the "insert" workflow with key None.

Acked-by: Esteban J. G. Gabancho <esteban.gabancho@gmail.com>
Acked-by: Jiri Kuncar <jiri.kuncar@cern.ch>
Signed-off-by: Jan Aage Lavik <jan.age.lavik@cern.ch>