[ticket/11854] Remove unused globals

PHPBB3-11854
[ticket/11854] Fix the factory in \phpbb\auth\provider\db

PHPBB3-11854
[ticket/11854] Base the migration on rc2

PHPBB3-11854
[ticket/11854] Fix comments

PHPBB3-11854
[ticket/11854] Change the error message in reCaptcha

PHPBB3-11854