[MUON] add default values for number of MFT-MCH matching candidates

The default number of matching candidates to be saved in output AO2Ds
is set to 5 for pp and 20 for Pb-Pb. For other beam typoes it is set
to zero, which prevents from adding the FwdMatching.saveMode and
FwdMatching.nCandidates options to the forward matching workflow.

Setting the MUON_MATCHING_NCANDIDATES environment variable ovverrides the
default values.

Author: aferrero2707

DATA/common/setenv.sh

@@ -169,8 +169,15 @@ ITSMFT_STROBES=""
 [[ ! -z ${ITS_STROBE:-} ]] && ITSMFT_STROBES+="ITSAlpideParam.roFrameLengthInBC=$ITS_STROBE;"
 [[ ! -z ${MFT_STROBE:-} ]] && ITSMFT_STROBES+="MFTAlpideParam.roFrameLengthInBC=$MFT_STROBE;"
 
-MFTMCH_NCANDIDATES_OPT=
-[[ ! -z ${MUON_MATCHING_NCANDIDATES:-} ]] && MFTMCH_NCANDIDATES_OPT+="FwdMatching.saveMode=3;FwdMatching.nCandidates=${MUON_MATCHING_NCANDIDATES};"
+# Number of MFT-MCH matching candidates to be stored in AO2Ds
+# Setting MUON_MATCHING_NCANDIDATES=0 disables the feature
+if [[ -z "${MUON_MATCHING_NCANDIDATES:-}" ]]; then
+  MUON_MATCHING_NCANDIDATES=0 # disable the saving of nCandidated by default
+  if [[ $BEAMTYPE == "pp" ]]; then MUON_MATCHING_NCANDIDATES=5; fi
+  if [[ $BEAMTYPE == "PbPb" ]]; then MUON_MATCHING_NCANDIDATES=20; fi
+fi
+MFTMCH_NCANDIDATES_OPT=""
+[[ "x${MUON_MATCHING_NCANDIDATES}" != "x0" ]] && MFTMCH_NCANDIDATES_OPT+="FwdMatching.saveMode=3;FwdMatching.nCandidates=${MUON_MATCHING_NCANDIDATES};"
 
 
 # Set active reconstruction steps (defaults added according to SYNCMODE)