Dropdown UX improvements

What does this MR do and why?

This improves a few dropdowns' UX by leveraging props that maybe weren't available when they were migrated to the new dropdown components.

Screenshots or screen recordings

Dropdown	Before	After
Global notification setting (/-/profile/notifications)
Groups notification settings (/-/profile/notifications)
Homepage user preference (/-/profile/preferences)
Language user preference (/-/profile/preferences)
Pipeline stage dropdown (any CI job in a mutli-stage pipeline)

How to set up and validate locally

Please refer to the table to see where those dropdowns can be seen within the app.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.