Keep cray-libsci in the EX testing environment (chapel-lang#26329)

In chapel-lang#23774, I unloaded
`cray-libsci` from the environment, possibly to avoid some issues with
GPU testing. With expanded testing on EX, we are seeing that we need
that module for some BLAS tests. Testing it again, I am observing that
some GPU tests are passing with that module loaded and BLAS tests work
fine. So, I am removing the explicit unload to observe the behavior over
a night's testing.

[Trivial fix for nightly runs, not reviewed]

util/cron/common-hpe-cray-ex.bash

@@ -11,9 +11,6 @@ module load PrgEnv-gnu/8.4.0
 module swap gcc gcc/12.2.0
 module load cray-pmi
 
-# cray-libsci currently has a problem on the Cray EX we run on
-module unload cray-libsci
-
 export CHPL_HOST_PLATFORM=hpe-cray-ex
 
 # Work around cxi provider bugs that limit memory registration