### What this PR does / why we need it?
The variables `self.prefiller_heap` `self.decoder_heap` are used as
`List[tuple[float, int, ServerState]]` but defined as `List[tuple[int,
int, ServerState]]`, which leads to the failed of mypy, see
https://github.com/vllm-project/vllm-ascend/actions/runs/21351411010/job/61448739554?pr=6265
### Does this PR introduce _any_ user-facing change?
### How was this patch tested?
- vLLM version: v0.14.1
- vLLM main:
d68209402d
Signed-off-by: wangli <wangli858794774@gmail.com>