OSS CI skip if xnnpack is not used (#1125)

Summary:
When we check for a model, we don't want jobs like test-models-macos (cmake, emformer_join, xnnpack, macos-m1-12) / macos-job which does nothing (non delegated nor quantized).

Pull Request resolved: https://github.com/pytorch/executorch/pull/1125

Reviewed By: huydhn

Differential Revision: D50896620

Pulled By: kirklandsign

fbshipit-source-id: ebd905dc6f37577fd17994abadcb21d51c81b0da