Change PyTorch tests to use non-default CUDA stream (#21474)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21474
ghimport-source-id: b2477765362248a80557d1a20db02a1290bdcde3
Differential Revision: D15699700
Pulled By: fbhuba
fbshipit-source-id: 1aa4309fec0982c8477cfab29ca5f42d2b171f97
