[ticket/11590] Close database connections when tearDown() is called

PHPBB3-11590
Merge pull request #1466 from nickvergessen/ticket/11590

[ticket/11590] Close database connections when tearDown() is called
Merge remote-tracking branch 'remotes/upstream/develop-olympus' into develop

# By Joas Schilling
# Via Joas Schilling (1) and Nils Adermann (1)
* remotes/upstream/develop-olympus:
  [ticket/11590] Close database connections when tearDown() is called