Adapt TBA translations to Mozilla naming scheme
In #29943 (moved) we moved locales of the type AB_CD to AB-CD and made sure all locales we support are available as Mozilla uses them in https://hg.mozilla.org/l10n-central.
(This is unrelated to the question how we can avoid duplication of Torbutton/TBA strings. However, we probably need that change for onboarding translations for 8.5)
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