Remove focus styles from dropdown empty link

What does this MR do?

EE MR, https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2839

Remove focus styles from dropdown empty link

New dropdowns style (move issue dropdown is from this MR)

Before	After

Old dropdowns style

Before	After

Search bar usage

Before	After

// Find/Add `window.search = this.initSearch();` in dispatcher.js
window.search.searchInput.trigger('focus')
window.search.restoreMenu()

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

The highlight was noticed here and UX already decided to remove.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Review
  • Has been reviewed by UX
  • Has been reviewed by Frontend
• Conform by the merge request performance guides
• Conform by the style guides
• Squashed related commits together

What are the relevant issue numbers?

Closes #37023 (closed)

---

cc @winh