add ATLAS specific path to LHAPATH and LHAPDF_DATA_PATH for correct functionality of Superchic
in order to make the new version of Superchic functional , additional pdf have to be available, they are loaded into /cvmfs/atlas.cern.ch/repo/sw/Generators/lhapdfsets/current, so we have to add this path into LHAPATH and LHAPDF_DATA_PATH. We add the path at the end of these paths to avoid misconfiguration problems we had in Athena project in February