### What this PR does / why we need it?
Remove draft model runner used for V0 spec decode.
This PR is a part of
https://github.com/vllm-project/vllm-ascend/issues/1620.
- vLLM version: v0.9.2
- vLLM main:
34cda778a0
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Signed-off-by: shen-shanshan <467638484@qq.com>