Ensure listener is done in testPendingConnectListeners

We need to ensure that we do not fail on InterruptedException in the
connection listener as this can happen when the connection is closed.

Closes #59879

server/src/test/java/org/elasticsearch/transport/RemoteClusterConnectionTests.java

@@ -1206,7 +1206,6 @@ public void onFailure(Exception e) {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/59879")
     public void testPendingConnectListeners() throws IOException, InterruptedException {
         List<DiscoveryNode> knownNodes = new CopyOnWriteArrayList<>();
         try (MockTransportService seedTransport = startTransport("seed_node", knownNodes, Version.CURRENT);
@@ -1225,6 +1224,7 @@ public void testPendingConnectListeners() throws IOException, InterruptedExcepti
                     ConnectionManager connectionManager = connection.getConnectionManager();
                     CountDownLatch connectionOpenedLatch = new CountDownLatch(1);
                     CountDownLatch connectionBlockedLatch = new CountDownLatch(1);
+                    CountDownLatch completionLatch = new CountDownLatch(1);
                     connectionManager.addListener(new TransportConnectionListener() {
                         @Override
                         public void onConnectionOpened(Transport.Connection connection) {
@@ -1233,6 +1233,8 @@ public void onConnectionOpened(Transport.Connection connection) {
                                 connectionBlockedLatch.await();
                             } catch (InterruptedException e) {
                                 throw new AssertionError(e);
+                            } finally {
+                                completionLatch.countDown();
                             }
                         }
                     });
@@ -1261,6 +1263,7 @@ public void onFailure(Exception e) {
                         }
                     } finally {
                         connectionBlockedLatch.countDown();
+                        completionLatch.await();
                         thread.join();
                     }
                 }