Update more personas handbook links

What does this MR do and why?

The personas page in our www-gitlab-com repo was moved at some point. This re-links our issue templates to the new location accordingly.

Follow-up to Updated the personas (!82823 - merged)

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.