Remove [no-mentions] handler in our triagebot config

https://github.blog/changelog/2025-11-07-removing-notifications-for-mentions-in-commit-messages/

Author: Urgau

src/tools/miri/triagebot.toml

@@ -53,8 +53,5 @@ new_draft = true
 # Canonicalize issue numbers to avoid closing the wrong issue when upstreaming this subtree.
 [canonicalize-issue-links]
 
-# Prevents mentions in commits to avoid users being spammed.
-[no-mentions]
-
 # Show range-diff links on force pushes.
 [range-diff]