### What this PR does / why we need it? The previous implementation of the flashcomm2 communication domain did not consider pp(pipeline parallel), which caused problems when enabling pp and flashcomm2. This PR fixes this issue. - vLLM version: v0.11.2 - vLLM main: https://github.com/vllm-project/vllm/commit/v0.11.2 --------- Signed-off-by: zzhx1 <zzh_201018@outlook.com> Co-authored-by: Levi-JQ <yujinqi2@huawei.com>