[Misc] Wait for next page to load in ApplicationCreatePage#clickNextStep

This is an attempt at fixing flickering in
WithoutScriptRightIT#createApplicationWithoutScriptRight which seems to
be caused by drag&drop operations starting before the class editor page
has been fully loaded.

(cherry picked from commit 2ec6cb6f)

xwiki-platform-core/xwiki-platform-appwithinminutes/xwiki-platform-appwithinminutes-test/xwiki-platform-appwithinminutes-test-pageobjects/src/main/java/org/xwiki/appwithinminutes/test/po/ApplicationCreatePage.java

@@ -138,7 +138,13 @@ public DocumentPicker getLocationPicker()
      */
     public ApplicationClassEditPage clickNextStep()
     {
+        // Make sure we actually wait for the page load to complete before returning.
+        getDriver().addPageNotYetReloadedMarker();
+
         clickNextStepButton();
+
+        getDriver().waitUntilPageIsReloaded();
+
         return new ApplicationClassEditPage();
     }