TriggerJobOpts: propagate LAr legacy flags to ConfigFlags in runHLT_standalone

TriggerJobOpts: propagate LAr legacy flags to ConfigFlags in runHLT_standalone

Hello,

When running RDOtoRDOTrigger with the legacy config, it seems that we do not set the LAr config flags correctly. In MC23, LAr flags are set by a preInclude, e.g. `--preInclude "all:Campaigns.MC23a"`, calling [Campaigns/share/MC23a.py](https://gitlab.cern.ch/atlas/athena/-/blob/main/Tools/Campaigns/share/MC23a.py), in turn calling [LArConfiguration/share/LArConfigRun3Old.py](https://gitlab.cern.ch/atlas/athena/-/blob/main/LArCalorimeter/LArConfiguration/share/LArConfigRun3Old.py). The jobproperties legacy flags are configured, but not propagated to [TriggerJobOpts/share/runHLT_standalone.py](https://gitlab.cern.ch/atlas/athena/-/blob/main/Trigger/TriggerCommon/TriggerJobOpts/share/runHLT_standalone.py) which rely on ConfigFlags. The mapping between legacy and config flags can be found in [thenaConfiguration/python/OldFlags2NewFlags.py](https://gitlab.cern.ch/atlas/athena/-/blob/main/Control/AthenaConfiguration/python/OldFlags2NewFlags.py#L109-127). After adding the mapping to runHLT_standalone, we get the following changes for MC23:
* flags.LAr.ROD.nSamples is now 4 instead of 5
* flags.LAr.ROD.UseHighestGainAutoCorr is now True instead of False
* flags.LAr.ROD.NumberOfCollisions is now 60 instead of 0

This bug is affecting the MC21a, MC23a and MC23c campaigns. It's impact is discussed in ATR-28590.

We don't expect the counts to change in the MC CI test, because the test doesn't specify a MC campaign in the preInclude...

The fix improves the agreement between CA and legacy configs (ATR-28470), the CA setup is not affected by the missing flag mapping.

Cheers,
Bertrand

Trigger/TriggerCommon/TriggerJobOpts/share/runHLT_standalone.py

@@ -167,7 +167,18 @@ flags.Detector.GeometryLucid = False
 
 from MuonRecExample.MuonRecFlags import muonRecFlags
 flags.Muon.enableNRPC = muonRecFlags.doNRPCs()
-    
+
+# Propagate LAr flags (Control/AthenaConfiguration/python/OldFlags2NewFlags.py)
+from LArConditionsCommon.LArCondFlags import larCondFlags
+from LArROD.LArRODFlags import larRODFlags
+flags.LAr.OFCShapeFolder = larCondFlags.OFCShapeFolder()
+flags.LAr.ROD.NumberOfCollisions = larRODFlags.NumberOfCollisions() if larRODFlags.doOFCPileupOptimization() else 0
+flags.LAr.ROD.nSamples = larRODFlags.nSamples()
+flags.LAr.ROD.FirstSample = larRODFlags.firstSample()
+flags.LAr.ROD.UseHighestGainAutoCorr = larRODFlags.useHighestGainAutoCorr()
+flags.LAr.ROD.DoOFCMixedOptimization = larRODFlags.doOFCMixedOptimization()
+flags.LAr.ROD.UseDelta = larRODFlags.UseDelta()
+flags.LAr.ROD.forceIter = larRODFlags.forceIter()
 
 # Increase scheduler checks and verbosity
 flags.Scheduler.CheckDependencies = True