don't apply marks directly in pytest

specifically - don't use `pytest.mark.xfail` directly in parametrize,
instead use `pytest.param(*args, marks=pytest.mark.xfail)`. the old way
is deprecated in pytest4 - for more information see
https://docs.pytest.org/en/latest/deprecations.html#marks-in-pytest-mark-parametrize

Also, make this an error in pytest.ini so if someone adds a new xfail,
it'll crash

pytest.ini

@@ -11,3 +11,6 @@ env =
     ZENDESK_API_KEY=test
     STATSD_PREFIX=stats-prefix
     REDIS_ENABLED=0
+
+filterwarnings =
+    error:Applying marks directly:pytest.RemovedInPytest4Warning