Add the energy loss fluctuation off to the G4Optimizations for mc23e

Add the energy loss fluctuation off to the G4Optimizations for mc23e. This MR will be undrafted only if the final green light on this optimization will be given by the MCP group. Follow up studies are ongoing here: https://its.cern.ch/jira/browse/ATLPHYSVAL-1022

cc @schaarsc @jchapman @whopkins @mnoury @mnovak

Simulation/SimuJobTransforms/python/G4Optimizations.py

@@ -32,6 +32,12 @@ def enableG4Optimizations(flags):
     flags.Sim.G4Commands+=["/process/em/UseGeneralProcess true"]
     flags.Sim.OptionalUserActionList += ['G4UserActions.G4UserActionsConfig.FixG4CreatorProcessToolCfg']
 
+    # Energy Loss fluctuation OFF
+    # Switch off the Energy loss fluctuation process
+    # More info: https://its.cern.ch/jira/browse/ATLASSIM-6995
+    flags.Sim.G4Commands+=["/process/eLoss/fluct false"]
+
+
     # Activate the Woodcock Tracking in the EMEC
     # Please note that the Woodcock tracking enables
     # the G4GammaGeneralProcess therefore the FixG4CreatorProcessTool