Set Trigger.EDMVersion to 3 if all POOL input files are empty
There is a corner case where we might have one or several input POOL files which are all empty. This may apparently happen in some grid merge jobs according to ADC experts. Ensure a valid (even if pointless) job configuration in this case by setting a valid (as opposed to the default) value of Trigger.EDMVersion
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Fixes ATR-24336. Tested as described in the ticket.