[CI] Add slow MPS tests (#1104)
* [CI] Add slow MPS tests
* fix yml
* temporarily resolve caching
* Tests: fix mps crashes.
* Skip test_load_pipeline_from_git on mps.
Not compatible with float16.
* Increase tolerance, use CPU generator, alt. slices.
* Move to nightly
* style
Co-authored-by: Pedro Cuenca <pedro@huggingface.co>
