test: use annotation to simplify register servlet

vul/vul-webapp-expression/src/main/java/MVELServlet.java

@@ -1,6 +1,7 @@
 import org.mvel2.MVEL;
 
 import javax.servlet.ServletException;
+import javax.servlet.annotation.WebServlet;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
@@ -10,6 +11,7 @@ import java.io.IOException;
  * @author ReaJason
  * @since 2024/12/14
  */
+@WebServlet("/mvel")
 public class MVELServlet extends HttpServlet {
     @Override
     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {