Ensure setup is only called once

It is called from the AsyncTestBase's @before.
No explicit teardown necessary, as Vert.x instances are closed
automatically via AsyncTestBase's @after.
Also not create more servers and clients than necessary.

Closes #5851

(cherry picked from commit a07b88f)

Author: ahus1

src/test/java/io/vertx/core/http/HttpBandwidthLimitingTest.java

@@ -69,9 +69,9 @@ public static Iterable<Object[]> data() {
     });
   }
 
-  private Function<Vertx, HttpServer> serverFactory;
-  private Function<Vertx, HttpClient> clientFactory;
-  private Function<Vertx, HttpServer> nonTrafficShapedServerFactory;
+  private final Function<Vertx, HttpServer> serverFactory;
+  private final Function<Vertx, HttpClient> clientFactory;
+  private final Function<Vertx, HttpServer> nonTrafficShapedServerFactory;
 
   public HttpBandwidthLimitingTest(double protoVersion, Function<Vertx, HttpServer> serverFactory,
                                    Function<Vertx, HttpClient> clientFactory,
@@ -81,21 +81,15 @@ public HttpBandwidthLimitingTest(double protoVersion, Function<Vertx, HttpServer
     this.nonTrafficShapedServerFactory = nonTrafficShapedServerFactory;
   }
 
-  @Before
+  @Override
   public void setUp() throws Exception {
     super.setUp();
+    server.close();
     server = serverFactory.apply(vertx);
+    client.close();
     client = clientFactory.apply(vertx);
   }
 
-  @After
-  public void after() throws InterruptedException
-  {
-    CountDownLatch waitForClose = new CountDownLatch(1);
-    vertx.close().onComplete(onSuccess(resp -> waitForClose.countDown()));
-    awaitLatch(waitForClose);
-  }
-
   @Test
   public void sendBufferThrottled() throws Exception {
     Buffer expectedBuffer = TestUtils.randomBuffer(TEST_CONTENT_SIZE);