Revert "Mute testRetentionPolicyChangeDuringRecovery"

This test is fixed by https://github.com/elastic/elasticsearch/pull/27947
This reverts commit cba80f3972d76f655a1a048aab1121b56f2b3a56.

core/src/test/java/org/elasticsearch/indices/recovery/RecoveryTests.java

@@ -68,7 +68,6 @@ public class RecoveryTests extends ESIndexLevelReplicationTestCase {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/27861")
     public void testRetentionPolicyChangeDuringRecovery() throws Exception {
         try (ReplicationGroup shards = createGroup(0)) {
             shards.startPrimary();