[HOT FIX] Stabilize macOS CI tests: OpenMP linking, MPI env, per-test isolation #4246

Job	Run time
pre-commit / pre-commit	1m 9s
windows / msvc-build (Release)	3m 34s
windows / clang-build	4m 10s
windows / msvc-build (Debug)	3m 30s
mac / clang-build (Debug)	2m 31s
mac / clang-build (Release)	3m 3s
ubuntu / clang-build (ubuntu-24.04)	2m 57s
ubuntu / clang-build (ubuntu-24.04-arm)	1m 54s
ubuntu / gcc-build (ubuntu-24.04, Release)	2m 12s
ubuntu / gcc-build (ubuntu-24.04-arm, Debug)	1m 54s
ubuntu / gcc-build (ubuntu-24.04, Debug)	2m 6s
ubuntu / gcc-build (ubuntu-24.04-arm, Release)	1m 56s
ubuntu / gcc-test (ubuntu-24.04)	8m 35s
ubuntu / gcc-test (ubuntu-24.04-arm)	8m 30s
ubuntu / clang-sanitizer-build (ubuntu-24.04)	3m 33s
ubuntu / clang-test (ubuntu-24.04)	8m 22s
ubuntu / clang-test (ubuntu-24.04-arm)	8m 33s
mac / clang-test	4m 50s
windows / msvc-test	5m 14s
windows / clang-test	3m 22s
ubuntu / clang-sanitizer-test (ubuntu-24.04)	2m 51s
windows / clang-test-extended	3m 5s
mac / clang-test-extended	2m 57s
windows / msvc-test-extended	2m 56s
ubuntu / clang-sanitizer-test-extended (ubuntu-24.04)	2m 26s
ubuntu / gcc-test-extended (ubuntu-24.04)	4m 30s
ubuntu / gcc-test-extended (ubuntu-24.04-arm)	4m 29s
ubuntu / clang-test-extended (ubuntu-24.04-arm)	4m 40s
ubuntu / clang-test-extended (ubuntu-24.04)	4m 34s
ubuntu / gcc-build-codecov	7m 32s
perf / ubuntu-gcc-build-perf-stats	1m 31s
perf / macos-clang-build-perf-stats	1m 46s
pages / build-doxygen-xml	1m 43s
pages / build-scoreboard	18s
pages / build-sphinx	2m 42s
pages / deploy-pages	0s
	2h 9m 55s

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