fix job splitting for ACDC MCFakeFile

This commit should fix two things (do NOT merge yet):
 a) when creating production jobs out of ACDC documents ( for MCFakeFile), do not use the fileset/lfn number of events (it corresponds to 250 jobs actually). Instead, create a job to recover only those missing lumis.
 b) take into account changes applied to the job splitting (EventBased) set for the new ACDC workflow -> TO BE FIXED