[ticket/12703] Only query database for subscription types once

PHPBB3-12703
Merge pull request #3076 from marc1706/ticket/12703

[ticket/12703] Only query database for subscription types once

* marc1706/ticket/12703:
  [ticket/12703] Only query database for subscription types once
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/12703] Only query database for subscription types once