Release update

• prevent reading previous metadata file, if one is missing
• update release to latest nightly, because 32 is broken for rates processing:

  File "/cvmfs/atlas.cern.ch/repo/sw/software/22.0/Athena/22.0.32/InstallArea/x86_64-centos7-gcc8-opt/bin/RatesAnalysisPo
stProcessing.py", line 73, in <module>
    main()
  File "/cvmfs/atlas.cern.ch/repo/sw/software/22.0/Athena/22.0.32/InstallArea/x86_64-centos7-gcc8-opt/bin/RatesAnalysisPo
stProcessing.py", line 59, in main
    L1Triggers = populateTriggers(inputFile, metadata, L1GlobalGroup, 'L1_')
  File "/cvmfs/atlas.cern.ch/repo/sw/software/22.0/Athena/22.0.32/InstallArea/x86_64-centos7-gcc8-opt/python/RatesAnalysi
s/Util.py", line 151, in populateTriggers
    triggerList.append( RatesTrigger(triggerKey.GetName(), metadata, hist.ReadObj(), globalGroup) )
  File "/cvmfs/atlas.cern.ch/repo/sw/software/22.0/Athena/22.0.32/InstallArea/x86_64-centos7-gcc8-opt/python/RatesAnalysi
s/RatesTrigger.py", line 41, in __init__
    self.passMasterWeighted = masterGroup.GetBinContent(RatesBins.PASS_WEIGHTED_OR_BIN.value)
AttributeError: 'NoneType' object has no attribute 'GetBinContent'

tagging @tamartin