### What this PR does / why we need it?
When use mtp, full decdoe only and async_scheduling together, finding a
input err for FIA ops due to the non-increasing input
of the 'actual_seq_lengths'. This bug is caused by the filling the
variable ‘query_start_loc’. We need to fill the query_start_loc' s end
by the 'cu_num_tokens' instead of '-1'
### 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>
ff0a1e012a