Moving the L1Sim pufit calculation to use the new code from TrigEFMissingET

This shifts the calculation from using a copied version from the old code to using the new HLT helper functions. The main difference with offline is that the grid structure is slightly different (12 eta bins rather 14) to align with the L1 towers.

https://gitlab.cern.ch/atlas/athena/blob/21.3/Event/xAOD/xAODTrigL1Calo/Root/JGTower_v1.cxx#L152-155

As an aside. This code really needs fixing. This caused the program to hang and was extremely hard to debug.