[MCH] add cut random fraction setting for the cases with and without ITS

Two new environment variables are introduced to provide the fraction of
rejected MCH events separately for the cases where the selection based
on ITS IRframes is either enabled (CUT_RANDOM_FRACTION_MCH_WITH_ITS) or
disabled (CUT_RANDOM_FRACTION_MCH_NO_ITS).

The selection based on ITS is enabled by default in SYNC processing for
physics runs where ITS is included in the data taking. It can be however
explicitely disabled by adding MCH_DISABLE_ITS_IRFRAMES_SELECTION=1 to
the custom environment variables. In this case, CUT_RANDOM_FRACTION_MCH_NO_ITS
is used.

The CUT_RANDOM_FRACTION_MCH variable, as well as the two new ones, can still
be overridden by setting them explicitly in the shell environment.
Moreover, the ITS selection is applied whenever MCH_DISABLE_ITS_IRFRAMES_SELECTION
is undefined, therefore the changes are fully backward compatible.

Author: aferrero2707

prodtests/full-system-test/dpl-workflow.sh

@@ -379,7 +379,12 @@ if has_processing_step MUON_SYNC_RECO; then
   elif [[ $RUNTYPE == "PHYSICS" && $BEAMTYPE == "pp" || $LIGHTNUCLEI == "1" ]] || [[ $RUNTYPE == "COSMICS" ]]; then
     MCH_CONFIG_KEY+="MCHTracking.chamberResolutionX=0.4;MCHTracking.chamberResolutionY=0.4;MCHTracking.sigmaCutForTracking=7.;MCHTracking.sigmaCutForImprovement=6.;"
   fi
-  has_detector_reco ITS && [[ $RUNTYPE != "COSMICS" ]] && MCH_CONFIG_KEY+="MCHTimeClusterizer.irFramesOnly=true;"
+  if has_detector_reco ITS && [[ $RUNTYPE != "COSMICS" && x"${MCH_DISABLE_ITS_IRFRAMES_SELECTION:-}" != "x1" ]]; then
+    MCH_CONFIG_KEY+="MCHTimeClusterizer.irFramesOnly=true;"
+    [[ -z ${CUT_RANDOM_FRACTION_MCH:-} && -n ${CUT_RANDOM_FRACTION_MCH_WITH_ITS:-} ]] && CUT_RANDOM_FRACTION_MCH=${CUT_RANDOM_FRACTION_MCH_WITH_ITS:-}
+  else
+    [[ -z ${CUT_RANDOM_FRACTION_MCH:-} && -n ${CUT_RANDOM_FRACTION_MCH_NO_ITS:-} ]] && CUT_RANDOM_FRACTION_MCH=${CUT_RANDOM_FRACTION_MCH_NO_ITS:-}
+  fi
   [[ -n ${CUT_RANDOM_FRACTION_MCH:-} ]] && MCH_CONFIG_KEY+="MCHTimeClusterizer.rofRejectionFraction=$CUT_RANDOM_FRACTION_MCH;"
   MCH_CONFIG_KEY+="MCHStatusMap.useHV=false;MCHDigitFilter.statusMask=3;"
   [[ $RUNTYPE == "COSMICS" ]] && [[ -z ${CONFIG_EXTRA_PROCESS_o2_mft_reco_workflow:-} ]] && CONFIG_EXTRA_PROCESS_o2_mft_reco_workflow="MFTTracking.FullClusterScan=true"