[Chapel Merge] Purge modules before loading the ones we want on C

Branch: refs/heads/master
Revision: 021a573
Author: ronawho
Log Message:

Merge pull request #17494 from ronawho/module-purge-cray-cs

Purge modules before loading the ones we want on Cray CS testing

[reviewed by @gbtitus]

Historically, these machines have had pretty bare-bones default modules,
but with some recent changes more modules including mpich are loaded by
default. That causes gasnet to detect mpi/mpirun and use that for a
launcher, but we want to be using ssh on these systems. For now just
purge all modules before loading the ones we want.

Modified Files:
M util/cron/common-cray-cs.bash

Compare: https://github.com/chapel-lang/chapel/compare/4afcdc023d72...021a573390b7