WIP: AOD reductions for release 21 - object thinning

ATLASRECTS-3820

This MR removes, via the thinning service, the following objects:
(1) Most Geant truth particles
(2) Negative energy calo clusters
(3) Negative energy neutral PFOs
This is achieved by setting the following properties to True in AODFlags: ThinGeantTruth, ThinNegativeEnergyCaloClusters, ThinNegativeEnergyNeutralPFOs
Since the thinning service is used, these objects are still built, but are not committed to the output xAOD.
This MR puts another of the recommendation of the AOD size task force into effect.


Former-commit-id: 9306490c945679810ade083d261f4815ac25ee9c