preferredLanguages dropdown doesn't allow you to add removed languages back

[mooreds]

preferredLanguages dropdown doesn't allow you to add removed languages back

Description

If you remove a preferredLanguage then try to add it back in it's not in the drop down list until you leave the page and then return. (Which is the workaround.)

Affects versions

1.24.0

Steps to reproduce

1. Go to the user edit screen in the admin UI
2. Add swedish and german to the preferred languages
3. Save the user
4. Edit the user
5. Remove swedish
6. Whoops, I want swedish, try to add it back

You can't add it back until you save the user, then edit the record again.

Expected behavior

Would be great to be able to have swedish back without the workaround.

Screenshots

If applicable, add screenshots to help explain your problem.

Platform

See this on FF and Safari on the mac.

Additional context

Add any other context about the problem here.