Resolve "Redirect back to "new release" page after creating milestone"

What does this MR do and why?

When creating a milestone from the new release page, you will get redirected back to the new release page once the milestone has been created.

Screenshots or screen recordings

How to set up and validate locally

1. Go to the 'new release' page to create a new release
2. In the milestone dropdown, choose 'create milestone'
3. Fill in milestone data and submit
4. Notice how you are redirected back to the new release page

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.

Related to #296084 (closed)