PyTorch removes legacy proto.ps1 script for Windows build cleanup

PyTorch has merged pull request #187507, which removes and desyncs the proto.ps1 script from the repository. This script was only used to build caffe2.proto on Windows, but that code has already been deleted from PyTorch a while back, making the script entirely obsolete. The commit was tagged by maintainer malfet and approved by albanD and atalman. A corresponding desync change (D108801228) ensures synchronization with the internal build system.

While this is a minor housekeeping change, it reflects ongoing efforts to streamline PyTorch’s build infrastructure and eliminate legacy dependencies. By removing unused components, the team reduces maintenance overhead and potential confusion for developers building PyTorch on Windows. It also signals a continued migration away from older Caffe2-era code that still lingered in the build toolchain. For most PyTorch users, no functional impact is expected, but the change improves code cleanliness and build reliability.