TE-572 disable flaky test.

This test has become unreliable. More info can be found in the JIRA ticket.

lms/djangoapps/courseware/features/problems.feature

@@ -115,7 +115,8 @@ Feature: LMS.Answer problems
         | drop down         | incorrect     | never           |
         | multiple choice   | incorrect     | never           |
         | checkbox          | incorrect     | never           |
-        | radio             | incorrect     | never           |
+        # TE-572
+        #| radio             | incorrect     | never           |
         #| string            | incorrect     | never           |
         | numerical         | incorrect     | never           |
         | formula           | incorrect     | never           |