Support Quasi-stable particle simulation in ComponentAccumulator-based Configuration
(Follows on from !46570 (merged).)
CA-based configuration changes to properly support FullG4MT_QS configuration. Add test_RUN3Sym_FullG4MT_QS_ttbar_CAvsCG.sh ART test to confirm this.
This also removed the legacy MC12G4 configurations, which are no longer supported.