[Lens] Stabilize FTR test (elastic#202476)

## Summary

Fixes elastic#200120

The navigation bar is not focused for some reason. Making it wait a bit
seems to stabilize it.

### 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

x-pack/test/functional/apps/lens/group2/persistent_context.ts

@@ -73,9 +73,11 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
           await visualize.gotoVisualizationLandingPage();
           await listingTable.searchForItemWithName('lnsTableVis');
           await lens.clickVisualizeListItemTitle('lnsTableVis');
-          await navigationalSearch.focus();
-          await navigationalSearch.searchFor('type:application lens');
-          await navigationalSearch.clickOnOption(0);
+          await retry.try(async () => {
+            await navigationalSearch.focus();
+            await navigationalSearch.searchFor('type:application lens');
+            await navigationalSearch.clickOnOption(0);
+          });
           await lens.waitForEmptyWorkspace();
           await lens.switchToVisualization('lnsLegacyMetric');
           await lens.dragFieldToWorkspace('@timestamp', 'legacyMtrVis');