SimuJobTransforms+FullChainTransforms: Stop forcing MaxFileSizes in job skeletons
A while back we had a discussion on the file size limits (see ATEAM-776). As a result, we dropped the hardcoded 15 GB limit from
AthenaPoolCnvSvc in !47626 (merged). However, as discussed more recently in ATLMCPROD-9870, some merge job skeletons are explicitly setting it (for - what looks like - historical reasons). In this MR, we also drop these.