Removal of old frontier servers and castor script settings from zp GROUP environment variables.

Based on a request as per https://its.cern.ch/jira/browse/ATLINFR-4900 We would like to have some old variables removed from the /etc/hepix scripts.

As suggested by Jan Iven, we have forked and made the changes and are now requesting that they are put into production after our experts have tested.

If there is anything else please let us know.