Fix default value in MakeZEffTree.cc

The default value of the triggersToMatch_ was
"process.hltEle17CaloIdVTCaloIsoVTTrkIdTTrkIsoVTSC8PMMassFilter", it is
now "hltEle17CaloIdVTCaloIsoVTTrkIdTTrkIsoVTSC8PMMassFilter".