fix(ollama/chat): correctly map reasoning_effort to think in requests

[kowyo]

Title

fix(ollama/chat): correctly map reasoning_effort to think in requests

Relevant issues

Fixes #15059

Fixes #11680 (#11680 (comment))

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Type

🐛 Bug Fix

Changes

Parameter mapping improvements:
Updated map_openai_params in both chat/transformation.py and completion/transformation.py so the reasoning_effort parameter maps directly to the Ollama think param (high/medium/low) instead of always defaulting to True. As in ollama/ollama-python@aa4b476 and ollama/ollama#11752.

Parameter mapping correction:
pop the think parameter from optional_params, so that it maps correctly to ollama API https://github.com/ollama/ollama/blob/main/docs/api.md, fixes the warning level=WARN source=types.go:737 msg="invalid option provided" option=think

Effect

Before this PR:

reasoning_content is missing from output, indicating that think param is not mapped correctly:

#15059

With this PR:

reasoning_content is return correctly.

Testing Pass

Gemini and Cohere related test should not be affected in this PR

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[krrishdholakia]

Hey @kowyo i believe that parameter value (low/medium/high) only works for gpt-oss. Can we be more careful on when to use low/medium/high vs. a 'True' based on model?

[kowyo]

Hey @krrishdholakia, you are correct, thanks for the feedback.

I have made some adjustments and will only set thinking level for gpt-oss model family.

Let me know if further work is needed.