Remove python 2.7 specific ref images from testsuite #7356

Job	Run time
macos-12 appleclang13/C++17 py3.10 MacOS-12	30m 13s
Ubuntu latest releases gcc12 C++17 avx2 exr3.2 ocio2.3	6m 32s
macos-13 appleclang14/C++17 py3.11 MacOS-13	21m 35s
windows-2019 VS2019	19m 47s
Ubuntu bleeding edge gcc13 C++20 py3.10 OCIO/libtiff/exr-master boost1.74 avx2	6m 42s
macos-14 appleclang15/C++20 py3.11 MacOS-14-ARM	9m 34s
windows-2022 VS2022	20m 43s
VFX2020 gcc6/C++14 py3.7 boost1.70 exr2.4 ocio1.1	8m 47s
Ubuntu clang14 C++20 avx2 exr3.1 ocio2.1	9m 37s
VFX2021 gcc9/C++17 py3.7 boost1.73 exr2.5 ocio2.0	7m 46s
Ubuntu debug gcc9/C++17, sse4.2, exr2.4	9m 51s
VFX2021 clang10/C++14 avx2 exr2.5 ocio2.0	11m 55s
Ubuntu static libs gcc9 C++17 exr2.4	6m 3s
VFX2022 gcc9/C++17 py39 boost1.76 exr3.1 ocio2.1	11m 34s
Ubuntu clang-format	2m 21s
VFX2022 clang13/C++17 py39 avx2 exr3.1 ocio2.1	11m 17s
VFX2022 icc/C++17 py3.9 boost1.76 exr3.1 ocio2.1 qt5.15	10m 29s
VFX2022 icx/C++17 py3.9 boost1.76 exr3.1 ocio2.1 qt5.15	14m 34s
VFX2022 sanitizers	30m 10s
VFX2023 gcc11/C++17 py3.10 boost1.80 exr3.1 ocio2.2	8m 28s
VFX2024 gcc11/C++17 py3.11 boost1.82 exr3.2 ocio2.3	7m 25s
VFX2021 oldest/hobbled gcc9.3/C++17 py3.7 boost-1.66 exr-2.4 no-sse no-ocio	13m 35s
VFX2023 abi check	6m 43s
	4h 45m 41s

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