Testing: Removing leftover @AwaitsFix annotation

Since the update to HDRHistogram 2.1.6 this test was
forgotten to get the annotation removed in #12554.

core/src/test/java/org/elasticsearch/search/aggregations/metrics/HDRPercentileRanksIT.java

@@ -256,7 +256,6 @@ public class HDRPercentileRanksIT extends AbstractNumericTestCase {
 
     @Override
     @Test
-    @AwaitsFix(bugUrl="Fails with seed: B75FCDC119D90BBE, Colin to fix")
     public void testSingleValuedField_WithValueScript_WithParams() throws Exception {
         int sigDigits = randomSignificantDigits();
         Map<String, Object> params = new HashMap<>();