### What problem does this PR solve?
https://github.com/infiniflow/ragflow/issues/9177
The reason should be due to the gemin internal use a different parameter
name
`
        max_output_tokens (int):
            Optional. The maximum number of tokens to include in a
            response candidate.

            Note: The default value varies by model, see the
            ``Model.output_token_limit`` attribute of the ``Model``
            returned from the ``getModel`` function.

            This field is a member of `oneof`_ ``_max_output_tokens``.
`
### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)