There is lot of torchair code in model runner leading the code hard for
maintenance. We'll create new torchair_model_runner to split torchair
related logic. Following the workflow #2203
What's this PR do:
move `torchair` related logic into `_get_forward_metadata_across_dp` and
override it in torchair model runner
- vLLM version: v0.10.0
- vLLM main:
1b99028069
Signed-off-by: wangxiyuan <wangxiyuan1007@gmail.com>