Remove use of MPI wrappers for fms and mapl package.py scripts

[srherbener]

Description

This PR removes the use of the MPI wrappers on the FMS and MAPL package.py scripts. This was done to enable spack-stack builds on the Mac using apple-clang%15.x compilers.

I cherry picked the commit used in the PR into the authoritative spack repo https://github.com/spack/spack/pull/43726 to create this PR.

Issue(s) addressed

Partially addresses JCSDA/spack-stack/issues/1083

Dependencies

List the other PRs that this PR is dependent on: None

Impact

Expected impact on downstream repositories: None

Checklist

• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation (N/A)
• [ ] I have run the unit tests before creating the PR

[climbfuji]

Don't worry about the failing macOS unit tests, that is unrelated to your PR