Parallelize constraint group solving #217

Job	Run time
manylinux (min) (Dockerfile.manylinux_2_28_x86_64, quay.io/pypa/manylinux_2_28_x86_64, manylinux_...	38m 25s
tracy profiler (v6.14, ON)	15m 22s
manylinux (min) (Dockerfile.manylinux_2_28_aarch64-min, quay.io/pypa/manylinux_2_28_aarch64, many...	1h 45m 15s
manylinux (min) (Dockerfile.manylinux_2_28_ppc64le-min, quay.io/pypa/manylinux_2_28_ppc64le, many...	1h 39m 49s
ubuntu (jammy, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	13m 17s
manylinux (min) (Dockerfile.manylinux_2_28_s390x-min, quay.io/pypa/manylinux_2_28_s390x, manylinu...	1h 39m 44s
ubuntu (noble, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	12m 3s
ubuntu (oracular, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	19m 27s
manylinux	1s
	6h 43m 23s

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