Replace the custom conversion with the Acts Plugin one

[tmadlener]

The ACTS EDM4hep plugin offers a conversion from the ACTS EDM to EDM4hep:

See, e.g.
https://github.com/acts-project/acts/blob/main/Examples/Io/EDM4hep/src/EDM4hepTrackOutputConverter.cpp
and the conversion implementation:
https://github.com/acts-project/acts/blob/main/Plugins/EDM4hep/include/ActsPlugins/EDM4hep/EDM4hepUtil.hpp#L107-L205

I think it would make sense to use that instead of rolling our own (even though historically ours probably came first).