Thread safe trigger object storage for L1TopoSim
The L1Topo simulation uses a global storage arena for the trigger objects that are either created as input or produced during the topo simulation execution. This has been moved to be a thread_local arena. The full L1Topo simulation runs within the execute() method of a cloneable AthenaAlg.
Part of ATR-19783
Edited by Joerg Stelzer