Following up from T270732: Upgrade doctrine/dbal from 2.10.4 to 3.0.x for PHP 8.0 support, blocked on T261872: Drop PHP 7.2 & 7.3 support from MediaWiki master branch, once Wikimedia production is on 7.4...
When we drop PHP 7.2 support in master (like in MW 1.35), after WMF production is on 7.3... We can clean up the hacks in includes/libs/rdbms/database/DoctrineSchemaBuilderFactory.php, while removing support for doctrine/dbal < 3.0.0