Remove pre_build_script from windows conda build

[NicolasHug]

pre-build-script should be only be used for wheel builds

[pytorch-bot]

🔗 Helpful Links

🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/vision/8590

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❌ 8 New Failures

As of commit be2286d with merge base 8f73afa ():

NEW FAILURES - The following jobs have failed:

• Build Aarch64 Linux Wheels / pytorch/vision / upload / wheel-py3_9-cpu-aarch64 (gh)
  Unable to find any artifacts for the associated workflow
• Build Aarch64 Linux Wheels / pytorch/vision / upload / wheel-py3_9-cuda-aarch64cuda-aarch64 (gh)
  Unable to find any artifacts for the associated workflow
• CMake / windows (windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.10, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.11, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.12, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.9, windows.4xlarge, cpu) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128
• Tests / unittests-windows (3.9, windows.g5.4xlarge.nvidia.gpu, cuda, 11.8) / windows-job (gh)
  The process 'C:\Program Files\Git\cmd\git.exe' failed with exit code 128

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[github-actions]

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