Fix unstable tests (#11648)

* Fix unstable tests

uitest/src/test/java/com/vaadin/tests/components/datefield/DateFieldFocusTest.java

 package com.vaadin.tests.components.datefield;
 
-import static org.junit.Assert.assertEquals;
-
 import org.junit.Test;
+import org.openqa.selenium.By;
 
 import com.vaadin.testbench.elements.DateFieldElement;
 import com.vaadin.testbench.elements.TextFieldElement;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
+import static org.junit.Assert.assertEquals;
+
 public class DateFieldFocusTest extends MultiBrowserTest {
 
     @Test
         TextFieldElement textField = $(TextFieldElement.class).caption("second")
                 .first();
 
-        dateField.openPopup();
-        dateField.openPopup();
-
-        dateField.openPopup();
-        dateField.openPopup();
+        // open DateField popup
+        dateField.findElement(By.className("v-datefield-button")).click();
+        sleep(100);
+        // close DateField popup
+        dateField.findElement(By.className("v-datefield-button")).click();
+        sleep(100);
 
         assertEquals("1. focused", getLogRow(0));
-
         textField.focus();
-
         waitUntil(input -> "2. blurred".equals(getLogRow(0)));
     }
 }

uitest/src/test/java/com/vaadin/tests/components/datefield/DateTimeFieldEventOrderTest.java

 
         DateTimeFieldElement field = $(DateTimeFieldElement.class).first();
 
-        field.openPopup();
+        field.findElement(By.className("v-datefield-button")).click();
 
         List<WebElement> timeSelects = findElement(
                 By.className("v-datefield-calendarpanel-time"))

uitest/src/test/java/com/vaadin/tests/components/grid/GridEditorMultiselectTest.java

 package com.vaadin.tests.components.grid;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
-
 import java.util.List;
 
 import org.junit.Test;
 import com.vaadin.testbench.parallel.TestCategory;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+
 @TestCategory("grid")
 public class GridEditorMultiselectTest extends MultiBrowserTest {
 
         openTestURL();
         GridElement grid = openEditor();
         grid.getEditor().cancel();
+        sleep(100);
         assertCheckboxesEnabled(grid, true);
     }
 

uitest/src/test/java/com/vaadin/tests/elements/menubar/MenuBarUITest.java

 package com.vaadin.tests.elements.menubar;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
 import java.util.List;
 
 import org.junit.Before;
 import com.vaadin.testbench.elements.MenuBarElement;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
 public class MenuBarUITest extends MultiBrowserTest {
 
     @Override
         // The Edit menu will be opened by moving the mouse over the item (done
         // by clickItem). The first click then actually closes the menu.
         menuBar.clickItem("Edit");
+        sleep(100);
         menuBar.clickItem("Edit");
         assertFalse(isItemVisible("Save As.."));
         assertTrue(isItemVisible("Paste"));

uitest/src/test/java/com/vaadin/tests/elements/notification/NotificationCloseTest.java

 package com.vaadin.tests.elements.notification;
 
-import static org.junit.Assert.assertTrue;
-
 import java.util.List;
 
 import org.junit.Test;
 import com.vaadin.testbench.elements.NotificationElement;
 import com.vaadin.tests.tb3.MultiBrowserTest;
 
+import static org.junit.Assert.assertTrue;
+
 public class NotificationCloseTest extends MultiBrowserTest {
 
     @Override
         ButtonElement btn = $(ButtonElement.class).id(id);
         // show notification
         btn.click();
+        sleep(100);
         $(NotificationElement.class).get(0).close();
         List<NotificationElement> notifications = $(NotificationElement.class)
                 .all();