The CaloClusterStoreHelper had a few legacy methods to support pre-MT workflows. This MR deletes these methods and migrates the last remaining client (CalibHitToCaloCellTool) to DataHandles.
I am unsure if CalibHitToCaloCellTool is still used in practice, it is only linked from DerivationFrameworkEGamma/TruthCaloShowerDecorator. The cluster-building of it looks a bit fishy to me (might make sense on a single-electron sample w/o noise)