fix(openai): "No call message found" bug with gpt-oss-120b when using responses API

[ehtec]

Fixes #32885

[codspeed-hq]

CodSpeed Performance Report

Merging #33450 will not alter performance

_{Comparing ehtec:master (03093b7) with master (78903ac)¹}

Summary

✅ 6 untouched
⏩ 28 skipped²

Footnotes

1. No successful run was found on master (760fc3b) during the generation of this report, so 78903ac was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

2. 28 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩