Restrict test CA requests to localhost

Restrict caget and caput to localhost during molecule testing to make sure that the caget and caput commands used during molecule testing actually access PVs on the test system and not from somewhere else. In the previous sprint we had tests randomly failing because caget returned values from another IOC on CSLab and not from the one running on the test machine.

molecule/default/files/ca_helpers/caget

+export EPICS_CA_ADDR_LIST=localhost
+export EPICS_CA_AUTO_ADDR_LIST=NO
+export PATH=`ls -dr1 /epics/base-*/bin/linux-x86_64/ | head -1`:$PATH
+caget "$@"