[tests] make 2 tests device-agnostic

[faaany]

What does this PR do?

After Fix:

$ RUN_SLOW=1 TRANSFORMERS_TEST_DEVICE=xpu TRANSFORMERS_TEST_DEVICE_SPEC=spec.py pytest tests/test_modeling_utils.py::ModelUtilsTest::test_model_parallelism_gpt2 tests/models/blip_2/test_modeling_blip_2.py::Blip2ModelIntegrationTest::test_inference_t5_multi_accelerator
==================================================== test session starts =====================================================
platform linux -- Python 3.9.19, pytest-7.4.4, pluggy-1.4.0
rootdir: /soft/fanli/transformers
configfile: pyproject.toml
plugins: xdist-3.5.0, metadata-3.1.1, reportlog-0.4.0, anyio-4.2.0, excel-1.6.0, hypothesis-6.98.0, html-4.1.1, timeout-2.3.1, env-1.1.3
collected 2 items                                                                                                            

tests/test_modeling_utils.py .                                                                                         [ 50%]
tests/models/blip_2/test_modeling_blip_2.py .                                                                          [100%]
=============================================== 2 passed, 5 warnings in 11.19s ===============================================

Who can review?

@ArthurZucker

[ArthurZucker]

LGTM thanks for the contiued efforts!

[ArthurZucker]

It's still draft tho, should we merge?

[HuggingFaceDocBuilderDev]

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[faaany]

Hi @ArthurZucker, thanks for the review! Yes, let's merge it.