Trigger/TrigL1Upgrade folder content redistribution

The content of the folder Trigger/TrigL1Upgrade is better located in other packages

• FEX simulation code (FP flavor) is now located in Trigger/TrigT1/TrigT1CaloFexPerf (but in there it comes from 21.3)
• SCell checking code has been moved to LArCalorimeter/LArTest/LArSCellTest

Discussed and agreed upon in ATR-19799

cc: @fwinkl, @bcarlson, @damazio, @pavol