Fix splitting page issues

Duplicate argument keys cause the object returned to the reqmgr
to be an array. Make sure that there are no duplicate keys,
also display the correct values for EventAwareLumiBased splitting.
Also fix modification of max time for merge.

Fixes #4409
Fix display of output datasets

Datasets produced by output modules that are never stored in merged
area were still reported by the listOutputModules function of WMWorkload.
Fix that by adding a flag that clearly marks transient and permanent
output.

Fixes #4422