[ticket/11644] Skip phpbb_dbal_order_lower_test on MySQL 5.6

PHPBB3-11644
Merge remote-tracking branch 'remotes/igorw/ticket/11644' into develop-olympus

# By Igor Wiedler
# Via Igor Wiedler
* remotes/igorw/ticket/11644:
  [ticket/11644] Skip phpbb_dbal_order_lower_test on MySQL 5.6