[Dashboard] Fix flaky time picker tests (#156761)

Closes https://github.com/elastic/kibana/issues/155603

## Summary

For the test that failed above, the failure screenshot shows that we
weren't waiting long enough for the pie chart to load before calling
`expectEmptyPieChart`:


![image](https://user-images.githubusercontent.com/8698078/236501367-290f481c-d17b-4d0a-a696-f50020fbd605.png)

Rather than adding a `wait` for just the single failing test, I figured
we should probably **always** wait for the page and visualizations to
load when adding visualizations - so, I added
`dashboard.waitForRenderComplete` to any methods I could find in the
Dashboard page object and the Dashboard visualizations service where
panels were being added.

Note that, if adding a given visualization also requires navigating to
and from the Dashboard app, I also added
`header.waitUntilLoadingHasFinished` before
`dashboard.waitForRenderComplete` so that we can wait for the Dashboard
app to load first before ensuring the visualizations have also loaded.
This should hopefully prevent any **other** tests that rely on adding a
visualization to be less flaky.

### Flaky Test Runner

<a
href="https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2228"><img
src="https://user-images.githubusercontent.com/8698078/236513873-d97f7c61-e8ee-4f5f-b76d-13998e62dadc.png"/></a>

### Checklist
- [x] [Unit or functional
tests](https://www.elastic.co/guide/en/kibana/master/development-tests.html)
were updated or added to match the most common scenarios

### For maintainers

- [ ] This was checked for breaking API changes and was [labeled
appropriately](https://www.elastic.co/guide/en/kibana/master/contributing.html#kibana-release-notes-process)

test/functional/apps/dashboard/group1/create_and_add_embeddables.ts

@@ -205,7 +205,6 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
           const originalPanelCount = await PageObjects.dashboard.getPanelCount();
           expect(originalPanelCount).to.eql(0);
           await dashboardVisualizations.createAndEmbedMetric('Embedding Vis Test');
-          await PageObjects.dashboard.waitForRenderComplete();
           await dashboardExpect.metricValuesExist(['0']);
           const panelCount = await PageObjects.dashboard.getPanelCount();
           expect(panelCount).to.eql(1);
@@ -217,7 +216,6 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
             name: 'Embedding Markdown Test',
             markdown: 'Nice to meet you, markdown is my name',
           });
-          await PageObjects.dashboard.waitForRenderComplete();
           await dashboardExpect.markdownWithValuesExists(['Nice to meet you, markdown is my name']);
           const panelCount = await PageObjects.dashboard.getPanelCount();
           expect(panelCount).to.eql(2);

test/functional/apps/dashboard/group3/dashboard_time_picker.ts

@@ -129,6 +129,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         '2015-09-19 06:31:44.000',
         '2015-09-23 18:31:44.000'
       );
+      await PageObjects.dashboard.waitForRenderComplete();
       await pieChart.expectPieSliceCount(10);
     });
   });

test/functional/apps/dashboard/group5/empty_dashboard.ts

@@ -55,7 +55,6 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         name: 'Dashboard Test Markdown',
         markdown: 'Markdown text',
       });
-      await PageObjects.dashboard.waitForRenderComplete();
       await dashboardExpect.markdownWithValuesExists(['Markdown text']);
     });
 

test/functional/page_objects/dashboard_page.ts

@@ -664,6 +664,7 @@ export class DashboardPageObject extends FtrService {
 
   public async addVisualizations(visualizations: string[]) {
     await this.dashboardAddPanel.addVisualizations(visualizations);
+    await this.waitForRenderComplete();
   }
 
   public async setSaveAsNewCheckBox(checked: boolean) {

test/functional/services/dashboard/visualizations.ts

@@ -30,6 +30,8 @@ export class DashboardVisualizationsService extends FtrService {
     await this.dashboardAddPanel.clickAddNewEmbeddableLink('metrics');
     await this.visualize.clickVisualBuilder();
     await this.visualize.saveVisualizationExpectSuccess(name);
+    await this.header.waitUntilLoadingHasFinished();
+    await this.dashboard.waitForRenderComplete();
   }
 
   async createSavedSearch({
@@ -80,6 +82,7 @@ export class DashboardVisualizationsService extends FtrService {
       await this.dashboard.switchToEditMode();
     }
     await this.dashboardAddPanel.addSavedSearch(name);
+    await this.dashboard.waitForRenderComplete();
   }
 
   async createAndAddMarkdown({ name, markdown }: { name: string; markdown: string }) {
@@ -95,6 +98,8 @@ export class DashboardVisualizationsService extends FtrService {
       saveAsNew: false,
       redirectToOrigin: true,
     });
+    await this.header.waitUntilLoadingHasFinished();
+    await this.dashboard.waitForRenderComplete();
   }
 
   async createAndEmbedMetric(name: string) {
@@ -109,6 +114,8 @@ export class DashboardVisualizationsService extends FtrService {
     await this.testSubjects.click('savedObjectTitlelogstash-*');
     await this.testSubjects.exists('visualizesaveAndReturnButton');
     await this.testSubjects.click('visualizesaveAndReturnButton');
+    await this.header.waitUntilLoadingHasFinished();
+    await this.dashboard.waitForRenderComplete();
   }
 
   async createAndEmbedMarkdown({ name, markdown }: { name: string; markdown: string }) {
@@ -121,5 +128,7 @@ export class DashboardVisualizationsService extends FtrService {
     await this.visEditor.setMarkdownTxt(markdown);
     await this.visEditor.clickGo();
     await this.testSubjects.click('visualizesaveAndReturnButton');
+    await this.header.waitUntilLoadingHasFinished();
+    await this.dashboard.waitForRenderComplete();
   }
 }