fix small typo in switching off TestHepMC cut
it was found out that there is a small typo in the JOs, it is fixing it https://its.cern.ch/jira/browse/ATLMCPROD-8985
Edited by Christian Gutschow
it was found out that there is a small typo in the JOs, it is fixing it https://its.cern.ch/jira/browse/ATLMCPROD-8985