Define GeometryBackend for DD4Hep and DetDesc and use DataType=2024/Run3 when DetDesc is picked up from Run2Support

Keep the changes consistent with what the changes in LHCb!4516 (merged)

go with LHCb!4516 (merged) and Gauss!1056 (merged)

Include !58 (merged) and replaces !56 (closed)