Revert "[Disagg][Perf] Use NPU event sync instead of blocking tolist

[wangxiyuan]

…to avoid unintentional copy ops blocking across different NPU streams, improving disagg TTIT/TTFT (#2788)"

What this PR does / why we need it?

This reverts commit 6995a7b. We'll add it back once the issue is fixed.

related issue: #3195

How was this patch tested?

• vLLM version: v0.10.2
• vLLM main: vllm-project/vllm@52d0cb8

[github-actions]

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[gemini-code-assist]

Code Review

This pull request reverts a previous performance optimization that used NPU event synchronization to avoid blocking tolist() calls. The changes correctly remove the custom _to_list implementation and its associated test, reverting to the standard tolist() method. The revert is clean and complete, with all related code and tests being removed or reverted as expected. While this reintroduces a performance bottleneck for disaggregated setups, it is presumably done to fix a correctness or stability issue introduced by the optimization. No issues were found in the revert itself.