Ensure setup is only called once

Closes #5857

(cherry picked from commit 57b9c68)

Author: ahus1

src/test/java/io/vertx/core/VirtualThreadContextTest.java

@@ -33,7 +33,7 @@ public class VirtualThreadContextTest extends VertxTestBase {
 
   VertxInternal vertx;
 
-  @Before
+  @Override
   public void setUp() throws Exception {
     super.setUp();
     vertx = (VertxInternal) super.vertx;

src/test/java/io/vertx/core/eventbus/VirtualThreadEventBusTest.java

@@ -21,7 +21,7 @@ public class VirtualThreadEventBusTest extends VertxTestBase {
 
   VertxInternal vertx;
 
-  @Before
+  @Override
   public void setUp() throws Exception {
     super.setUp();
     vertx = (VertxInternal) super.vertx;

src/test/java/io/vertx/core/net/NetBandwidthLimitingTest.java

@@ -49,7 +49,7 @@ public class NetBandwidthLimitingTest extends VertxTestBase {
   private SocketAddress testAddress;
   private NetClient client = null;
 
-  @Before
+  @Override
   public void setUp() throws Exception {
     super.setUp();
     if (USE_DOMAIN_SOCKETS) {