Revert "Add OnCompletion Hook to ProcessGroup (#106988)"
This reverts commit ba1da47e8fa95ca0dd8b2d63430f7eb54fdbbccb.
Reverted https://github.com/pytorch/pytorch/pull/106988 on behalf of https://github.com/huydhn due to Sorry for reverting you change, but it is failing Windows build with some linker error. The Windows failures on PR looks legit ([comment](https://github.com/pytorch/pytorch/pull/106988#issuecomment-1678580899))
