Move away from using CERN-SWTEST
Adapts gauss-merge-genfsr test to not use the GRID storage element.
This fixes failing tests, such as https://lhcb-nightlies.web.cern.ch/nightly/lhcb-master/1585/Gauss/x86_64_v2-centos7-gcc11-opt/tests#Gauss.gauss-merge-genfsr
Edited by Rosen Matev