[DeepSeekV2] Fix integration tests OOM: use device_map=auto instead of 8-bit quantization (#47991)

* [DeepSeekV2] Fix integration tests: use device_map=auto, remove 8-bit quantization

The model (DeepSeek-V2-Lite) exceeds A10G VRAM even with 8-bit quantization.
Switch to device_map="auto" (bfloat16, no quantization) which offloads excess
weights to CPU. Update expected logit values accordingly.

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

* [DeepSeekV2] Update expected values for device_map=auto bfloat16 loading

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

* [DeepSeekV2] Fix curly apostrophe in batch_fa2 expected text, add tearDown cleanup

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

* [DeepSeekV2] Round expected logit values to 4 decimal places

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

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Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>
Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>