Parallelize constraint group solving #224

Job	Run time
ubuntu (jammy, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	14m 1s
ubuntu (noble, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	12m 34s
ubuntu (oracular, v6.14, linux/amd64,linux/arm64,linux/ppc64le,linux/s390x, OFF)	12m 25s
manylinux (min) (Dockerfile.manylinux_2_28_x86_64, quay.io/pypa/manylinux_2_28_x86_64, manylinux_...	38m 40s
manylinux (min) (Dockerfile.manylinux_2_28_aarch64-min, quay.io/pypa/manylinux_2_28_aarch64, many...	2h 2m 2s
manylinux (min) (Dockerfile.manylinux_2_28_ppc64le-min, quay.io/pypa/manylinux_2_28_ppc64le, many...	2h 1m 9s
manylinux (min) (Dockerfile.manylinux_2_28_s390x-min, quay.io/pypa/manylinux_2_28_s390x, manylinu...	1h 57m 28s
tracy profiler (v6.14, ON)	21m 17s
manylinux (Dockerfile.manylinux_2_28_aarch64, jslee02/dart-dev:manylinux_2_28_aarch64-min-v6.14, ...	4h 25m 24s
manylinux (Dockerfile.manylinux_2_28_ppc64le, jslee02/dart-dev:manylinux_2_28_ppc64le-min-v6.14, ...	4h 21m 53s
manylinux (Dockerfile.manylinux_2_28_s390x, jslee02/dart-dev:manylinux_2_28_s390x-min-v6.14, many...	4h 15m 48s
	20h 42m 41s

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