[Discover] Fix flaky Discover security functional test (#156221)

## Summary

Fixes #153796.

Flaky test runner x 100:
https://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/2196

### Checklist

- [ ] ~Any text added follows [EUI's writing
guidelines](https://elastic.github.io/eui/#/guidelines/writing), uses
sentence case text and includes [i18n
support](https://github.com/elastic/kibana/blob/main/packages/kbn-i18n/README.md)~
- [ ]
~[Documentation](https://www.elastic.co/guide/en/kibana/master/development-documentation.html)
was added for features that require explanation or tutorials~
- [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
- [ ] ~Any UI touched in this PR is usable by keyboard only (learn more
about [keyboard
accessibility](https://webaim.org/techniques/keyboard/))~
- [ ] ~Any UI touched in this PR does not create any new axe failures
(run axe in browser:
[FF](https://addons.mozilla.org/en-US/firefox/addon/axe-devtools/),
[Chrome](https://chrome.google.com/webstore/detail/axe-web-accessibility-tes/lhdoppojpmngadmnindnejefpokejbdd?hl=en-US))~
- [ ] ~If a plugin configuration key changed, check if it needs to be
allowlisted in the cloud and added to the [docker
list](https://github.com/elastic/kibana/blob/main/src/dev/build/tasks/os_packages/docker_generator/resources/base/bin/kibana-docker)~
- [ ] ~This renders correctly on smaller devices using a responsive
layout. (You can test this [in your
browser](https://www.browserstack.com/guide/responsive-testing-on-local-server))~
- [ ] ~This was checked for [cross-browser
compatibility](https://www.elastic.co/support/matrix#matrix_browsers)~

### 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)

x-pack/test/functional/apps/discover/feature_controls/discover_security.ts

@@ -431,6 +431,14 @@ export default function ({ getPageObjects, getService }: FtrProviderContext) {
           full_name: 'test user',
         });
 
+        // Navigate home before attempting to login or we may get redirected to
+        // Discover with a forbidden error, which hides the chrome and causes
+        // PageObjects.security.login to fail when checking for the logout button
+        await PageObjects.common.navigateToUrl('home', '', {
+          ensureCurrentUrl: false,
+          shouldLoginIfPrompted: false,
+        });
+
         await PageObjects.security.login(
           'no_discover_privileges_user',
           'no_discover_privileges_user-password',