[ticket/11573] Honor MySQL STRICT_TRANS_TABLES in test_style_select.

PHPBB3-11573
[ticket/11573] Honor MySQL STRICT_TRANS_TABLES in phpbb_user_loader_test.

PHPBB3-11573
Merge remote-tracking branch 'bantu/ticket/11573' into develop

* bantu/ticket/11573:
  [ticket/11573] Honor MySQL STRICT_TRANS_TABLES in phpbb_user_loader_test.
  [ticket/11573] Honor MySQL STRICT_TRANS_TABLES in test_style_select.