Turn XLA back on for default set (but filtered out using should_run_job) (#21470)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21470
ghimport-source-id: 69800c1ce1187591b7bcdb8a63973b4fd8d0e326
Differential Revision: D15696930
Pulled By: ezyang
fbshipit-source-id: fafbcba38d9572a23ee9c1d81cdcce3a154ae4c6
