test: remove AwaitsFix for field stats API test

This was fixed in core but the awaits fix was not removed here.

Original commit: elastic/x-pack-elasticsearch@357a797b5e

elasticsearch/x-pack/shield/src/test/java/org/elasticsearch/integration/FieldLevelSecurityTests.java

@@ -482,8 +482,6 @@ public class FieldLevelSecurityTests extends ShieldIntegTestCase {
         assertThat(response.getResponses()[0].getResponse().getSource().get("field2").toString(), equalTo("value2"));
     }
 
-    // norelease - we need to fix the issue so that only fields a user can see are returned
-    @AwaitsFix(bugUrl = "https://github.com/elastic/x-plugins/issues/2120")
     public void testFieldStatsApi() throws Exception {
         assertAcked(client().admin().indices().prepareCreate("test")
                         .addMapping("type1", "field1", "type=text", "field2", "type=text", "field3", "type=text")