SimuJobTransforms: Don't schedule EventInfoCnvAlg if xAOD EI already exists.
Don't schedule EventInfoCnvAlg if xAOD::EventInfo already exists in the input file. Otherwise, it gets remade anyway from the old EventInfo. And if the input file does not contain an old EventInfo, then we'll end up with an empty xAOD::EventInfo.
See ATLASSIM-5734.