t() calls should be avoided in classes, use dependency injection and $this->t() instead in example module

That controller and that test class are still calling t().

This patch correctly changes the code.

I also fixed the translated string: The correct sentence is The layout here is themed as a table that is sortable by clicking the header name., not The layout here is a themed as a table that is sortable by clicking the header name.

Automatically closed - issue fixed for 2 weeks with no activity.