feat: add Sonnet 4 and Sonnet 4.5 as selectable models to all classic Duo features

What does this merge request do and why?

Adds Sonnet 4.5 as selectable model for Duo Classic features to model selection on top-level group.

In addition, it also adds Sonnet 4 (on Anthropic API and on Vertex) as selectable model to Classic Duo features as some of only support outdated or soon to be deprecated model versions.

Model Selection (Classic Duo)	Langsmith

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.
• If this change requires executor implementation: verified that issues/MRs exist for both Go executor and Node executor or confirmed that changes are backward-compatible and don't break existing executor functionality.

Related to #1540 (closed)