[LLaVA] Fix pixtral integration tests for cuda sm_86 (#48166)

* [LLaVA] Fix pixtral integration tests for cuda sm_86

- test_pixtral: use device_map="auto" to avoid OOM on 22GB GPU, update
  expected output to ("cuda", 8) (stale value from torch 2.10 update)
- test_pixtral_4bit: replace ("cuda", 7)/("xpu", 3) with ("cuda", 8)
- test_pixtral_batched: replace (None, None) with ("cuda", 8)

All expected values verified on A10G (cuda sm_86).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* [LLaVA] Keep (None, None) originals alongside new ("cuda", 8) entries

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

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Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>