Fix for MT-safe mon in L1Topo ATR-19783
This is remaining task of the !34191 (merged) for fixing thread-unsafe L1Topo algorithms.
After the changes, AthenaMT output for L1Topo simulation is,
/afs/cern.ch/work/a/asonay/public/trig-test/expert-monitoring.root
Edited by Anil Sonay