Removed the selected user from ContactSearchScene upon addition

client/src/main/java/envoy/client/ui/controller/ContactSearchScene.java

@@ -118,7 +118,8 @@ public class ContactSearchScene {
 				final var event = new ContactOperation(user, ElementOperation.ADD);
 				// Sends the event to the server
 				eventBus.dispatch(new SendEvent(event));
-				// Updates the UI
+				// Removes the chosen user and updates the UI
+				userList.getItems().remove(user);
 				eventBus.dispatch(event);
 				logger.log(Level.INFO, "Added user " + user);
 			}));