Add additional developer support for fix

What does this MR do and why?

Asks the author of vulnerability fixes to provide the name of an additional developer who can help with merge or pipeline failures. Having additional coverage should reduce the risk of release delays.

Related to https://gitlab.com/gitlab-org/gitlab/-/issues/378913

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

How to set up and validate locally

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

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.