[ticket/11561] Specify used tables in notification fixture, so they are emptied

PHPBB3-11561
[ticket/11604] Use variables for config.php filesnames.

PHPBB3-11604
[ticket/11604] Fix case where config.php is not generated by phpBB.

PHPBB3-11604
Merge remote-tracking branch 'nickvergessen/ticket/11561' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/11561:
  [ticket/11561] Specify used tables in notification fixture, so they are emptied
Merge remote-tracking branch 'bantu/ticket/11604' into develop-olympus
Merge branch 'develop-olympus' into develop

Conflicts:
	tests/test_framework/phpbb_functional_test_case.php