TrigSteer → TrigCostMonitor Relation

File in Trigger/TrigSteer	Includes file in Trigger/TrigMonitoring/TrigCostMonitor
HLTSeeding / src / HLTSeeding.h	TrigCostMonitor / ITrigCostSvc.h
DecisionHandling / src / TriggerSummaryAlg.h	TrigCostMonitor / ITrigCostSvc.h