Configure Open MPI shmem defaults on macOS #4945

Job	Run time
ci-scope	6s
pre-commit / link-check	13s
pre-commit / pre-commit	2m 0s
mac / clang-build (Debug)	2m 46s
mac / clang-build (Release)	1m 58s
windows / msvc-build (Debug)	3m 52s
windows / msvc-build (Release)	3m 17s
windows / clang-build	2m 45s
ubuntu / gcc-build (ubuntu-24.04, Release)	2m 32s
ubuntu / clang-build (ubuntu-24.04)	3m 8s
ubuntu / gcc-build (ubuntu-24.04, Debug)	2m 17s
ubuntu / gcc-test (ubuntu-24.04)	2m 56s
windows / clang-test	1m 27s
mac / clang-test	1m 29s
ubuntu / clang-test (ubuntu-24.04)	2m 39s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	3m 15s
windows / msvc-test	2m 10s
windows / clang-test-extended	2m 0s
mac / clang-test-extended	1m 24s
ubuntu / gcc-test-extended (ubuntu-24.04)	1m 39s
ubuntu / clang-test-extended (ubuntu-24.04)	1m 45s
windows / msvc-test-extended	1m 16s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	1m 22s
ubuntu / gcc-build-codecov	4m 4s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	1m 0s
perf / ubuntu-gcc-build-perf-stats	1m 4s
perf / macos-clang-build-perf-stats	1m 24s
pages / build-doxygen-xml	34s
pages / build-scoreboard	20s
pages / build-sphinx	38s
pages / deploy-pages	0s
	57m 20s

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