Draft: Merge new components into old rather than old components into new
After the discussion in the configuration meeting of 3rd September 2021 on why the order of the Detector Tools in the GeoModelSvc.DetectorTools ToolHandleArrya was reversed in the CA-based configuration compared to the old-style configuration, we found an inconsistency in the deduplicate method, which merged existing components into new components, rather than new components into the existing versions.
This merge request changes that, so that the ordering now agrees (unfortunately it didn't fix the FATAL errors I was seeing though).
I'm leaving this as a draft for now in case there was some reason that the function was written in that way.