Change variant to confirm for save chages button (insights)

What does this MR do and why?

Updates the variant to confirm to match Pajamas guidelines

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Use GitLab Ultimate
2. Go to a group
3. Go to general settings /-/edit
4. View Save changes button

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.