DB Tools sql_column_exists() broken in postgresql

In postgresql, the sql_column_exists() method from db_tools is broken, and always returns false.

phpBB Debug] PHP Notice: in file [ROOT]/phpbb/db/tools/tools.php on line 925: Undefined variable: sql

[phpBB Debug] PHP Warning: in file [ROOT]/phpbb/db/driver/postgres.php on line 286: pg_fetch_assoc(): 28 is not a valid PostgreSQL result resource

boolean false

$sql on line 925 is undefined in postgresql. However, it appears that when using postgresql, the postgresql db_tools child class is never actually called.

it looks like the tools factory is not working as expected. When using a postgresql, the tools factory sees the db_driver as an instance of the phpbb\db\driver\factory, so the factory still loads the standard tools class instead of postgresql (or mssql).

This is major since this test is used in a lot of effectively installed checks in migrations.