Update TrackVertexAssociationTool.cxx
A dot was missing in the call of ReadDecorHandleKey, making the code crashing with this error (refer to https://gitlab.cern.ch/atlas-mcp/MuonPerformanceAnalysis/-/issues/11). This MR aims to fixing it.
AODtoDPD 14:00:05 ExceptionSvc DEBUG Handling std:except: "SG::ExcBadAuxVar: Attempt to retrieve nonexistent aux data item `::' (3050)."