### What this PR does / why we need it?
When enable the async_scheduling, in large scale EP scene, mtp module
goes to eagler mode, which results in the mismatch of
seq_lens_list、block_table. So adapt the judgement before the draft model
forward.
fix#4986
### Does this PR introduce _any_ user-facing change?
No
### How was this patch tested?
- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c
Signed-off-by: hust17yixuan <303660421@qq.com>