[TEST][ML] Reinstate date parsing test (#34634)

The test was muted due to a bug in an early access build of Java 11
https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8206980

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/job/config/DataDescriptionTests.java

@@ -53,11 +53,6 @@ public class DataDescriptionTests extends AbstractSerializingTestCase<DataDescri
         description.setTimeFormat("epoch");
         description.setTimeFormat("epoch_ms");
         description.setTimeFormat("yyyy-MM-dd HH");
-    }
-
-    @AwaitsFix(bugUrl = "https://bugs.java.com/bugdatabase/view_bug.do?bug_id=JDK-8206980")
-    public void testVerify_GivenValidFormat_Java11Bug() {
-        DataDescription.Builder description = new DataDescription.Builder();
         description.setTimeFormat("yyyy.MM.dd G 'at' HH:mm:ss z");
     }