Fix missing missing parameter extension test

[franmomu]

I've tried to add the SonataAdminExtension to getContainerExtensions, but there a couple of problems here with the load method.

First it is dependent on the order the extensions were declared, it should iterate the extensions first and call prepend and then iterate them again and call load.

And then if you pass to the load method: $this->load(['document_tree' => []]);, both extension will try to load this configuration which is wrong.

So this is why I added sonata.admin.configuration.use_intl_templates parameter directly.

Ref: SymfonyTest/SymfonyDependencyInjectionTest#78

[greg0ire]

Thanks @franmomu !