[FX] s/IS_SANDCASTLE/IS_FBCODE/ in tests (#61304)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61304
Previously tests were unrunnable on devserver. This fixes that
ghstack-source-id: 133051811
Test Plan: waitforsadcastle
Reviewed By: Chillee
Differential Revision: D29561806
fbshipit-source-id: 6020e5b4ba72d6de1ea2563e70fdb0e604bee1a5
