[Mistral3] Fix batched integration tests: padding_side=left + update expected values (#48161)

[Mistral3] Fix batched integration tests: set padding_side=left, update expected values

- Set `processor.tokenizer.padding_side = "left"` in both batched tests to fix
  incorrect generation caused by right-padding with position ID tracking change
  introduced in #43734. Right padding caused the model to ignore instructions.
- Update stale expected values for cuda sm_86 across all 3 integration tests,
  verified on A10G (CUDA 8.6, torch 2.13).

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