ci: Streamline the old MacOS-12 CI test (#4465) #16

Job	Run time
Ubuntu latest releases gcc13 C++20 py3.12 avx2 exr3.2 ocio2.3	12m 48s
macos-12 appleclang13/C++17 py3.11 MacOS-12	18m 53s
Ubuntu bleeding edge gcc14 C++20 py3.12 OCIO/libtiff/exr-main avx2	6m 48s
macos-13 appleclang14/C++17 py3.11 MacOS-13	19m 36s
VFX2021 gcc9/C++17 py3.7 exr3.1 ocio2.0	10m 29s
Ubuntu all local builds gcc12 C++17 avx2 exr3.2 ocio2.3	13m 55s
macos-14 appleclang15/C++20 py3.12 MacOS-14-ARM	10m 56s
VFX2021 clang10/C++17 avx2 exr3.1 ocio2.0	10m 47s
Ubuntu clang14 C++20 avx2 exr3.1 ocio2.1	11m 42s
VFX2022 gcc9/C++17 py39 exr3.1 ocio2.1	10m 43s
Ubuntu debug gcc9/C++17, sse4.2, exr3.1	13m 56s
VFX2022 clang13/C++17 py39 avx2 exr3.1 ocio2.1	6m 5s
Ubuntu static libs gcc9 C++17 exr2.4	5m 55s
windows-2019 VS2019	50m 59s
VFX2022 icc/C++17 py3.9 exr3.1 ocio2.1 qt5.15	11m 6s
Ubuntu clang-format	3m 4s
VFX2022 icx/C++17 py3.9 exr3.1 ocio2.2 qt5.15	9m 27s
windows-2022 VS2022	47m 58s
VFX2024 sanitizers	33m 27s
VFX2023 gcc11/C++17 py3.10 exr3.1 ocio2.2	11m 12s
VFX2024 gcc11/C++17 py3.11 exr3.2 ocio2.3	12m 13s
VFX2021 oldest gcc9.3/C++17 py3.7 exr-3.1	13m 16s
VFX2021 hobbled gcc9.3/C++17 py3.7 exr-3.1 no-sse	13m 34s
VFX2023 abi check	6m 30s
	6h 5m 19s

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