[ticket/13033] Fix "Duplicate entry 'notification.type.*' for key 'type'"

Caused by the solution of PHPBB3-12990

PHPBB3-13033
Merge pull request #3017 from nickvergessen/ticket/13033

[ticket/13033] Fix "Duplicate entry 'notification.type.*' for key 'type'"
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13033] Fix "Duplicate entry 'notification.type.*' for key 'type'"