use existing socket binding in AddMessagingConnectorOnlineTest

It worked before WildFly 30 because restart was required to actually apply changes (and it would fail after restart), but after [WFLY-18237](https://issues.redhat.com/browse/WFLY-18237) the validation happens immmediately.

testsuite/standalone/src/test/java/org/wildfly/extras/creaper/commands/messaging/AddMessagingConnectorOnlineTest.java

@@ -63,7 +63,7 @@ public void addInVmConnector() throws CommandFailedException, IOException {
     @Test
     public void addGenericConnector() throws CommandFailedException, IOException {
         AddMessagingConnector addMessagingConnector = new AddMessagingConnector.GenericBuilder(TEST_CONNECTOR)
-                .socketBinding("testSocketBinding")
+                .socketBinding("http")
                 .factoryClass("testClass")
                 .build();
 
@@ -79,7 +79,7 @@ public void addGenericConnector() throws CommandFailedException, IOException {
     @Test
     public void addRemoteConnector() throws CommandFailedException, IOException {
         AddMessagingConnector addMessagingConnector = new AddMessagingConnector.RemoteBuilder(TEST_CONNECTOR)
-                .socketBinding("testSocketBinding")
+                .socketBinding("http")
                 .build();
 
         client.apply(addMessagingConnector);