[TEST] Mmm, still wrap wrappers still its needed post closing dir

previous push was partial by mistake, we still need the wrapped dirs around after being closed for the test infra, for now, explicitly clear it in the leak test (which is still bad apple)

src/test/java/org/elasticsearch/indices/leaks/IndicesLeaksTests.java

@@ -28,6 +28,7 @@ import org.elasticsearch.index.shard.IndexShard;
 import org.elasticsearch.indices.IndicesService;
 import org.elasticsearch.test.ElasticsearchIntegrationTest;
 import org.elasticsearch.test.ElasticsearchIntegrationTest.ClusterScope;
+import org.elasticsearch.test.store.MockDirectoryHelper;
 import org.junit.Test;
 
 import java.lang.ref.WeakReference;
@@ -91,6 +92,7 @@ public class IndicesLeaksTests extends ElasticsearchIntegrationTest {
         shardInjector = null;
 
         cluster().wipeIndices("test");
+        MockDirectoryHelper.wrappers.clear(); // we need to clear this to allow the objects to recycle
 
         for (int i = 0; i < 100; i++) {
             System.gc();

src/test/java/org/elasticsearch/test/store/MockDirectoryHelper.java

@@ -141,7 +141,6 @@ public class MockDirectoryHelper {
                 synchronized (lock) {
                     lock.notifyAll();
                 }
-                wrappers.remove(this);
             }
         }