gromacs spack concretization error on rzvernal

[rfhaque]

gromacs throws a spack concretizer error on rzvernal. The exact same configuration works on tioga. The issue affects both the rocm and openmp builds on rzvernal

==> Error: concretization failed for the following reasons:

   1. Cannot set the required compiler: gromacs%cce
   2. Attempted to use external for 'cray-mpich' which does not satisfy any configured external spec
   3. Attempted to build package cray-mpich which is not buildable and does not have a satisfying external
        attr('variant_value', 'cray-mpich', 'gtl', 'True') is an external constraint for cray-mpich which was not satisfied
   4. Attempted to build package cray-mpich which is not buildable and does not have a satisfying external
        attr('node_compiler_version_satisfies', 'cray-mpich', 'cce', '16.0.0') is an external constraint for cray-mpich which was not satisfied
   5. Attempted to build package cray-mpich which is not buildable and does not have a satisfying external
        attr('node_compiler', 'cray-mpich', 'cce') is an external constraint for cray-mpich which was not satisfied. You could consider setting `concretizer:unify` to `when_possible` or `false` to allow multiple versions of some packages.
==> Error: Command exited with status 1:

To reproduce:

1. get the feature/gromacs branch
2. initialize the system: bin/benchpark system init --dest=rzvernal llnl-elcapitan rocm=5.5.1 compiler=cce +gtl lapack=intel-oneapi-mkl blas=intel-oneapi-mkl
3. initialize gromacs: bin/benchpark experiment init --dest ./gromacs-rocm gromacs +openmp+rocm~cuda gpu-aware-mpi=force
4. benchpark setup: bin/benchpark setup gromacs-rocm rzvernal <workspace_dir>
5. . <workspace_dir>/setup.sh
6. ramble --disable-progress-bar --workspace-dir <workspace_dir>/gromacs-rocm/LlnlElcapitan-6e1a6ba/workspace workspace setup

[pearce8]

@rfhaque please re-test now that #572 has been merged.

[rfhaque]

@rfhaque please re-test now that #572 has been merged.

I'm getting the same error on rzvernal