Language selector drop down should not list languages for which we don't have a translation file

[deborahgu]

Expected behavior

If there are no available translations, we should not list of the languages in the drop-down.

Actual behavior

We list languages for which we do not have translation files.

Steps to reproduce

1. Open up account settings
2. Click or scroll to "Site Preferences".
3. Click "Edit" next to "Site language".
4. Note the list of languages. You should be able to use your browser's element inspector to see the complete list here, including the ISO 639 language codes.
5. Note that the following are all available in the list:
   • ca (Catalan)
   • fr (French, as opposed to Canadian French, which does exist)
   • ko-kr (Korean)
   • pl (Polish)
6. Look in https://github.com/openedx/openedx-translations/tree/main/translations/frontend-app-account/src/i18n/messages and note that none of those have corresponding translations

Conditions of Acceptance

The contents of the drop down match the contents of the translations directory.