compiler: Revamp MPI hoisting and merging #8033

Job	Run time
pytest-ubuntu-py311-gcc11-cxxnoomp-adjoint	37m 48s
pytest-ubuntu-py312-gcc12-cxxomp-adjoint	46m 48s
pytest-ubuntu-py311-gcc11-cxxnoomp-base	51m 32s
pytest-ubuntu-py310-gcc10-noomp-base	48m 5s
pytest-ubuntu-py312-gcc12-cxxomp-base	1h 3m 7s
pytest-ubuntu-py39-gcc14-omp-adjoint	38m 41s
pytest-ubuntu-py39-gcc14-omp-base	52m 17s
pytest-ubuntu-py310-gcc10-noomp-adjoint	34m 35s
pytest-ubuntu-py312-gcc13-omp-base	58m 57s
pytest-osx-py312-clang-omp-base	33m 0s
pytest-ubuntu-py39-gcc9-omp-adjoint	38m 25s
pytest-docker-py39-gcc-omp-adjoint	32m 45s
pytest-ubuntu-py39-gcc9-omp-base	50m 8s
pytest-ubuntu-py312-gcc13-omp-adjoint	43m 8s
pytest-docker-py39-icx-omp-adjoint	32m 29s
pytest-docker-py39-gcc-omp-base	43m 55s
pytest-docker-py39-icx-omp-base	35m 33s
	12h 21m 13s

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