Fix ISF_HepMC_Tools unit tests (ATLASSIM-7301)
!74633 (merged) had some unexpected consequences for the ISF_HepMC_Tools unit tests. Namely that Monopoles now pass MC::isInteracting(...)
rather than having to be named as an additional interacting particle type - this breaks one of the unit tests. The failing test has been commented out for now, until we decide on a different pdgCode to use for testing. There was also a typo in the isMonopole(...)
function which has also been fixed.
Should fix ATLASSIM-7301