[Bug] Qwen reasoning parser

[ahao-anyscale]

Purpose

When running with Qwen/Qwen3-30B-A3B, reasoning_content is empty despite correctly formed <think> tag. Relevant issue: ray-project/ray#57919

Test Plan

Run requests with Qwen/Qwen3-30B-A3B and observe that reasoning_content is populated instead of content.

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