Use fixed width in integration test for stability (#9560)

Fix table width to match the reference screenshot.

test/servlet-containers/generic/src/main/java/com/vaadin/tests/integration/ServletIntegrationUI.java

@@ -32,6 +32,7 @@ public class ServletIntegrationUI extends UI {
         table.setSelectable(true);
         table.setVisibleColumns(new Object[] { "country" });
         layout.addComponent(table);
+        table.setWidth("112px");
 
         Item item = table.addItem("FI");
         item.getItemProperty("icon").setValue(new ClassResource("fi.gif"));