Wrong default value for "framework.form.enabled" config node

[chalasr]

As of Symfony 3.3 the framework.form.enabled config option is default true false if you are requiring symfony/symfony, but documentation says it is always false by default (https://symfony.com/doc/current/reference/configuration/framework.html#reference-form-enabled).

Originally reported on symfony/symfony#24269
Also applies to assets, validation, translation, serialization and csrf

[stof]

The issue description is wrong. It defaults to true when you are not using symfony/symfony and symfony/form is installed (i.e. a Flex-like project using forms)

[chalasr]

Indeed, mistake. PR body updated.

[javiereguiluz]

Fixed by #8468.