Add deadline to fakelowp tests (#48823)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48823
deadline=None is not good because
Sandcastle tests will return success for tests timeout (default flag), and we cannot efficiently detect broken tests if there is any.
In addition, the return signal for timeout is 64, which is same as skip test.
Test Plan: Sandcastle, and run tests on card
Reviewed By: hyuen
Differential Revision: D25318184
fbshipit-source-id: de1b55a259edb2452fb51ba4c598ab8cca9e76b7
