Protection from crash in HSGNN code
This MR includes a protection from crashes in the code if the tool is scheduled together the diphoton vertex selection tool, as in the latter the sumPt decorator is written without using WriteDecorHandleKeys (see https://gitlab.cern.ch/atlas/athena/-/blob/main/PhysicsAnalysis/ElectronPhotonID/PhotonVertexSelection/Root/PhotonVertexSelectionTool.cxx#L277).