Use mpi-extensions main Open MPI in CI #5078

Job	Run time
pre-commit / link-check	16s
pre-commit / pre-commit	2m 48s
ci-scope	7s
mac / clang-build (Release)	2m 30s
windows / clang-build	2m 41s
windows / msvc-build (Release)	5m 4s
ubuntu / gcc-build (ubuntu-26.04, Debug)	2m 26s
windows / msvc-build (Debug)	3m 49s
ubuntu / gcc-build (ubuntu-26.04, Release)	3m 2s
mac / clang-build (Debug)	3m 8s
ubuntu / clang-build (ubuntu-26.04)	3m 28s
windows / clang-test	2m 11s
ubuntu / gcc-test (ubuntu-26.04)	2m 48s
mac / clang-test	2m 11s
ubuntu / clang-sanitizer-build (ubuntu-26.04)	3m 22s
ubuntu / clang-test (ubuntu-26.04)	2m 43s
windows / clang-test-extended	1m 39s
windows / msvc-test	2m 1s
mac / clang-test-extended	-1s
ubuntu / gcc-test-extended (ubuntu-26.04)	1m 1s
ubuntu / clang-test-extended (ubuntu-26.04)	33s
ubuntu / gcc-build-codecov	1s
ubuntu / clang-sanitizer-test	1s
ubuntu / clang-sanitizer-test-extended	1s
windows / msvc-test-extended	1s
perf	0s
pages	-1s
	47m 50s

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