ATR-19016: Merge Level-1 Trigger Athena packages from release 21 to master
requested to merge l1calo-run3-simulation/athena:ATR-19016_merge_TrigT1_from_21.0-TrigMC_to_master into master
This MR merges changes L1Trigger changes from 21.0-TrigMC branch into master.
For more info: https://its.cern.ch/jira/browse/ATR-19016
Closes ATR-19016