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

• Issue: As https://lhcb-nightlies.web.cern.ch/nightly/lhcb-sim11-run5/10/Gauss/x86_64_v2-el9-gcc12-opt/tests showned, all dd4hep tests are failred as they are trying to access git:///Conditions/Online/valid_runs.txt. It is unreasonable because DD4hep does not use conditions.

• Reason: In LHCb, UseDD4Hep is a compile time constant, while in Gauss it is decided at runtime.

• Solution: DDDB should be removed form Run2Support, keep it only at LHCb, but it will take a long time to implement as some Gauss/Gaussion tasks are still rely on that. And this issue is blocking the progress of DD4hep related work, especially blocking the merge request for Upgrade2 new sub-detector's merge requst in Detector (we can not test them). A kind of temporary solution is introduce a new properties, Geometrybackend, for the Geometry.

• Another change: Use DataType=2024/Run3 when DetDesc is picked up from Run2Support

Work with Run2Support!58 (merged) and Gauss!1056 (merged)

Includes !4388 (closed)

@gcorti @clemenci