FIX: Only staff can edit topic details when first post is locked (PR #10729)

This is addressing the meta topic here https://meta.discourse.org/t/user-able-to-edit-title-of-locked-post-still-again-possible/164547?u=markvanlan

GitHub

This pull request has been mentioned on Discourse Meta. There might be relevant details there:

https://meta.discourse.org/t/user-able-to-edit-title-of-locked-post-still-again-possible/164547/12