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
In principle this case should never happen, since we do not create longer jobs in the ACDC compared to the original request (it should be the other way around). Even it this happen, it may not be optimal to have a smaller job but it's also not harmful. So I would say we are good here. Unless I missed some detail (?)