ATR-20345 Update CostMonitoringChain in L1Decoder.h
Update default name of CostMon chain to HLT_costmonitor_CostMonDS_L1All
Based on having the final name from !27239 (merged)
This property isn't currently used, CostMon currently runs in every event. But in the future we only want to run it in events where this trigger is active.