Fix flaky console tests (#208337)

Fixes https://github.com/elastic/kibana/issues/204381

## Summary
The test that verifies tab changes in Console was failing because it was
verifying the presence of the tab content before it was fully loaded.


### Checklist
- [x] [Flaky Test
Runner](https://ci-stats.kibana.dev/trigger_flaky_test_runner/1) was
used on any tests changed

Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>

src/platform/plugins/shared/console/public/application/containers/main/main.tsx

@@ -311,6 +311,7 @@ export function Main({ currentTabProp, isEmbeddable = false }: MainProps) {
         <EuiSplitPanel.Inner
           paddingSize="none"
           css={[scrollablePanelStyle, { backgroundColor: euiTheme.colors.body }]}
+          data-test-subj="consolePanel"
         >
           {currentTab === SHELL_TAB_ID && (
             <Editor

test/functional/apps/console/_console.ts

@@ -89,8 +89,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
       });
     });
 
-    // FLAKY: https://github.com/elastic/kibana/issues/204381
-    describe.skip('tabs navigation', () => {
+    describe('tabs navigation', () => {
       let currentUrl: string;
 
       beforeEach(async () => {
@@ -125,6 +124,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         currentUrl = await browser.getCurrentUrl();
         log.debug('Current URL: ' + currentUrl);
         expect(currentUrl).to.contain(`/history`);
+        await PageObjects.header.waitUntilLoadingHasFinished();
         expect(await PageObjects.console.isHistoryOpen()).to.be(true);
 
         // Navigate to Config tab via URL
@@ -132,6 +132,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         currentUrl = await browser.getCurrentUrl();
         log.debug('Current URL: ' + currentUrl);
         expect(currentUrl).to.contain(`/config`);
+        await PageObjects.header.waitUntilLoadingHasFinished();
         expect(await PageObjects.console.isConfigOpen()).to.be(true);
 
         // Navigate to Shell tab via URL
@@ -139,6 +140,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         currentUrl = await browser.getCurrentUrl();
         log.debug('Current URL: ' + currentUrl);
         expect(currentUrl).to.contain(`/shell`);
+        await PageObjects.header.waitUntilLoadingHasFinished();
         expect(await PageObjects.console.isShellOpen()).to.be(true);
       });
     });

test/functional/page_objects/console_page.ts

@@ -311,16 +311,23 @@ export class ConsolePageObject extends FtrService {
     await this.testSubjects.click('consoleHistoryButton');
   }
 
+  async isConsoleTabOpen(tabId: string) {
+    await this.retry.waitFor('console container is displayed', async () => {
+      return await this.testSubjects.isDisplayed('consolePanel');
+    });
+    return await this.testSubjects.exists(tabId);
+  }
+
   public async isShellOpen() {
-    return await this.testSubjects.exists('consoleEditorContainer');
+    return await this.isConsoleTabOpen('consoleEditorContainer');
   }
 
   public async isConfigOpen() {
-    return await this.testSubjects.exists('consoleConfigPanel');
+    return await this.isConsoleTabOpen('consoleConfigPanel');
   }
 
   public async isHistoryOpen() {
-    return await this.testSubjects.exists('consoleHistoryPanel');
+    return await this.isConsoleTabOpen('consoleHistoryPanel');
   }
 
   public async openSettings() {