Reduce timing on CircleCI - part 1 (Use @slow for IntegrationTests)

[ydshieh]

What does this PR do?

Reduce timing on CircleCI.

Use @slow for some IntegrationTests.

Note that, for IntegrationTest class that have setupClass, even if a test method is fast, the setupClass might still take quite long time, if it downloads models. Even tokenizers may take 3 -5 seconds sometimes

[github-actions]

[For maintainers] Suggested jobs to run (before merge)

run-slow: aria, bark, hiera, imagegpt, jamba, llava, mamba, mbart, olmo2, plbart, rag, rt_detr, rt_detr_v2, speech_to_text, speecht5, tvp

[HuggingFaceDocBuilderDev]

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