Fix for some tests running twice
All tests from slapos.test.recipe module were executed twice since https://lab.nexedi.com/nexedi/slapos/commit/f8de4cc4b6f7eae12f9140a33591ac90e07912f6 when running as python setup.py test
python setup.py test --test-suite slapos.test.test_recipe.additional_tests still runs only tests for recipes and python setup.py test runs tests for recipe and static tests for software releases (for now json schema).