Use correct listener in dependency filter test

This fixes the test after the changes in #9368

test/dependency-rewrite-addon/src/main/java/com/vaadin/test/dependencyrewriteaddon/RewriteJQueryFilter.java

@@ -5,10 +5,13 @@ import java.util.List;
 import java.util.Locale;
 
 import com.vaadin.server.DependencyFilter;
+import com.vaadin.server.ServiceInitEvent;
+import com.vaadin.server.VaadinServiceInitListener;
 import com.vaadin.ui.Dependency;
 import com.vaadin.ui.Dependency.Type;
 
-public class RewriteJQueryFilter implements DependencyFilter {
+public class RewriteJQueryFilter
+        implements DependencyFilter, VaadinServiceInitListener {
 
     @Override
     public List<Dependency> filter(List<Dependency> dependencies,
@@ -25,4 +28,10 @@ public class RewriteJQueryFilter implements DependencyFilter {
         }
         return filtered;
     }
+
+    // for compactness, implementing the init listener here
+    @Override
+    public void serviceInit(ServiceInitEvent event) {
+        event.addDependencyFilter(this);
+    }
 }