[Bugfix][PD]fix non-working disaggregated prefill

[CaveNightingale]

What this PR does / why we need it?

Mainline vLLM fixes its disaggregated prefill in vllm-project/vllm#22598 . But it is still not working in vllm-ascend.
To be concrete, decoder instances crash before vllm's fix and hang after vllm's fix in ascend devices.
This patch allows disaggregated prefill to work.

Does this PR introduce any user-facing change?

No.

How was this patch tested?

Qwen3-0.6B 1P1D tp=1 dp=1

• vLLM version: v0.10.0
• vLLM main: vllm-project/vllm@0fe8508

[gemini-code-assist]

Code Review

This pull request aims to fix a bug in disaggregated prefill for vllm-ascend, which was causing hangs. The change introduces version-specific logic to handle differences in the ModelRunnerOutput API between vLLM versions. My review found a potential issue with the version checking mechanism, which could lead to crashes on older vLLM versions because it uses an exact version match, which is brittle.

[github-actions]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
⚠️ Please upload report for BASE (main@1b40665). Learn more about missing BASE report.
⚠️ Report is 643 commits behind head on main.

Additional details and impacted files

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unittests	76.18% <ø> (?)

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[wangxiyuan]

quick merge to recover PD functin. The CI failure doesn't relate to this PR