dsl: Fix SubDomainSet auxiliary dimension name to avoid clashes #8678

Job	Run time
pytest-ubuntu-py311-gcc10-noomp-base	37m 35s
pytest-ubuntu-py310-gcc14-omp-base	41m 13s
pytest-ubuntu-py312-gcc13-omp-base	47m 53s
pytest-ubuntu-py312-gcc12-cxxomp-adjoint	36m 17s
pytest-ubuntu-py311-gcc11-cxxnoomp-adjoint	29m 49s
pytest-ubuntu-py311-gcc11-cxxnoomp-base	41m 26s
pytest-ubuntu-py312-gcc12-cxxomp-base	52m 16s
pytest-ubuntu-py311-gcc10-noomp-adjoint	27m 39s
pytest-ubuntu-py310-gcc9-omp-base	41m 8s
pytest-ubuntu-py310-gcc9-omp-adjoint	29m 48s
pytest-ubuntu-py310-gcc14-omp-adjoint	30m 3s
pytest-docker-py310-gcc-omp-base	35m 47s
pytest-osx-py312-clang-omp-base	32m 36s
pytest-ubuntu-py313-gcc14-omp-base	49m 1s
pytest-docker-py310-icx-omp-adjoint	26m 28s
pytest-docker-py310-icx-omp-base	29m 39s
pytest-ubuntu-py313-gcc14-omp-adjoint	36m 5s
pytest-docker-py310-gcc-omp-adjoint	25m 41s
pytest-ubuntu-py312-gcc13-omp-adjoint	33m 18s
	11h 23m 42s

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