Fix EntityFilter cascading domain validation via grid criteria root form

[adpeyre]

Problem

The grid filter form validates the selected entity as if it were a real domain object, even though it shouldn't — a filter is just a search criterion, not a form meant to create or edit an entity. When the filtered entity has its own Assert constraints (e.g. NotBlank), this shows validation errors on form submission that have nothing to do with the actual filter.

Root cause

The criteria root form built in TwigGridRenderer::renderFilter() has no data_class — its data is a plain array. Symfony's FormValidator runs its automatic data-graph validation only on the root form, and for a plain array it validates each contained object against its own class constraints. entity is the only filter type whose value is such an object, so it's the only one affected.

Fix

Set 'validation_groups' => false on the criteria root form in TwigGridRenderer::renderFilter(), since it's a rendering container, not a validated business form.