Better mocking of services in tests because of deprecated code

[NKPmedia]

We need a better way to mock services in the tests.
The actual way is marked as:

Setting the "reCaptcha" pre-defined service is deprecated since Symfony 3.3 and won't be supported anymore in Symfony 4.0: 2x
1x in FeedbackControllerTest::testCreateFeedbackDatabaseEntry from Tests\AppBundle\Controller
1x in FeedbackControllerTest::testCreateFeedbackDatabaseEntryWithLoggedInUser from Tests\AppBundle\Controller

For the moment I marked the tests with Legacy to avoid problems while testing on circleci.