E2E: saving a dashboard should wait for success (#18171)

- navigating right away triggered the unsaved warning on slower machines
- this change makes sure we see a success message first

public/e2e-test/pages/dashboards/saveDashboardModal.ts

@@ -4,17 +4,20 @@ import {
   Selector,
   InputPageObjectType,
   InputPageObject,
+  PageObject,
 } from 'e2e-test/core/pageObjects';
 import { TestPage } from 'e2e-test/core/pages';
 
 export interface SaveDashboardModal {
   name: InputPageObjectType;
   save: ClickablePageObjectType;
+  success: PageObject;
 }
 
 export const saveDashboardModal = new TestPage<SaveDashboardModal>({
   pageObjects: {
     name: new InputPageObject(Selector.fromAriaLabel('Save dashboard title field')),
     save: new ClickablePageObject(Selector.fromAriaLabel('Save dashboard button')),
+    success: new PageObject(Selector.fromSelector('.alert-success')),
   },
 });

public/e2e-test/scenarios/smoke.test.ts

@@ -57,6 +57,7 @@ e2eScenario(
     const dashboardTitle = new Date().toISOString();
     await saveDashboardModal.pageObjects.name.enter(dashboardTitle);
     await saveDashboardModal.pageObjects.save.click();
+    await saveDashboardModal.pageObjects.success.exists();
 
     // Share the dashboard
     const dashboardsPage = dashboardsPageFactory(dashboardTitle);