### What this PR does / why we need it?
support qwen3-next full_decode_only mode.
bs=1, max_token=1024
| branch| tps| e2e time|
| --- | --- | --- |
|piecewise |3.06 | 8.15 |
|fulldecodeonly | 7.2 | 3.47 |
- vLLM version: v0.11.0
- vLLM main:
83f478bb19
Signed-off-by: wangxiaoxin-sherie <wangxiaoxin7@huawei.com>
Co-authored-by: wangxiaoxin-sherie <wangxiaoxin7@huawei.com>