Don't remove driver options when extending a grid configuration

[loic425]

Based on #317

<?php

use App\Entity\Suplier;
use Sylius\Bundle\GridBundle\Builder\GridBuilder;
use Sylius\Bundle\GridBundle\Config\GridConfig;

return static function (GridConfig $grid) {
    $grid->addGrid(
        GridBuilder::create('sylius_admin_product_variant')
    );
};

When running this following command:

$ bin/console debug:config sylius_grid grids.sylius_admin_product_variant.driver

Before

name: doctrine/orm
options: {  }

After

name: doctrine/orm
options:
    class: App\Entity\Product\ProductVariant
    repository:
        method: createQueryBuilderByProductId
        arguments:
            - "expr:service('sylius.context.locale').getLocaleCode()"
            - $productId

[GSadee]

Thanks, Loïc! 🥇