Change model used in git_command LLM endpoint

What does this MR do and why?

This changes the feature to use Claude 3 Haiku.

https://gitlab.com/gitlab-org/cli/-/issues/7596

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshot

How to set up and validate locally

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

Using glab CLI run: GITLAB_HOST=http://gdk.test:3000 glab duo ask list last 10 commit title. Set GITLAB_HOST to whatever the of your GDK.