Fix and Dequarantine WebIDE empty directory test

What does this MR do?

The test was failing due to change in selector from a.monaco-description-button to a.monaco-text-button may be introduced in !115743 (merged). Fixed that and ensured that the spec passes locally, so Dequarantined this test

E2E Test Failure issue(s)

See #399544 (closed)

How to set up and validate locally

QA_LOG_LEVEL=DEBUG bundle exec rspec qa/specs/features/browser_ui/3_create/web_ide/add_new_directory_in_web_ide_spec.rb

Check-list

• General code guidelines check-list
  • Code review guidelines
  • Style guides
• Quarantine test check-list
  • Follow the Quarantining Tests guide.
  • Confirm the test has a quarantine: tag with the specified quarantine type.
  • Note if the test should be quarantined for a specific environment.
  • (Optionally) In case of an emergency (e.g. blocked deployments), consider adding labels to pick into auto-deploy (Pick into auto-deploy priority1 severity1).
• Dequarantine test check-list
  • Follow the Dequarantining Tests guide.
  • Confirm the test consistently passes on the target GitLab environment(s).
• To ensure a faster turnaround, ask in the #quality_maintainers Slack channel for someone to review and merge the merge request, rather than assigning it directly.