Revert "Increased compile time max GPUs to 512. Switched to int16_t DeviceIndex. (#119639)"
This reverts commit 7c556428c74a79c6d9c272826344a0828d3f66f5.
Reverted https://github.com/pytorch/pytorch/pull/119639 on behalf of https://github.com/kit1980 due to breaking internal builds, see D54286923 ([comment](https://github.com/pytorch/pytorch/pull/119639#issuecomment-1969634480))
