feat(openai): add `max_tokens` to `AzureChatOpenAI` (#32959)
Fixes #32949
This pattern is [present in
`ChatOpenAI`](https://github.com/langchain-ai/langchain/blob/master/libs/partners/openai/langchain_openai/chat_models/base.py#L2821)
but wasn't carried over to Azure.
[CI](https://github.com/langchain-ai/langchain/actions/runs/17741751797/job/50417180998)
