Mention events should display the name of the wiki where they took place in Notifications

STEPS TO REPRODUCE

1. Login as Admin
2. Create a subwiki
3. Create a global user (e.g. U1) on Main Wiki
4. Login as U1
5. Go to Notifications Settings and turn Mentions toggles to ON (make sure Watch toggles are also ON)
6. Login as Admin
7. Go to subwiki
8. Mention the global user U1 on a page
9. Go to Main Wiki
10. Login with U1 and observe the notifications list

EXPECTED RESULTS

Due to the fact that the user U1 is viewing the notifications on Main Wiki, the Mention event has the name of the subwiki (where it took place) displayed near its title, like the other type of events have.

ACTUAL RESULTS

The mention event is missing the name of the subwiki where it took place, although the notifications list is viewed on Main Wiki.