Add Sim.FastCalo.RunOnGPU ConfigFlag (ATLASSIM-6896)
Further case of legacy jobproperties being accessed in the FastCaloSimV2 configuration.
Added a new Sim.FastCalo.RunOnGPU ConfigFlag which should be set instead of ISF_FastCaloSimFlags.RunOnGPU in ComponentAccumulator-based jobs. This flag is only written out to the simulation metadata in the case that we are running Fast Calorimeter Simulation.
Fixes ATLASSIM-6896 according to my local tests, but I thought that was the case after !66150 (merged) too (as did the CI)...