Conflicting updates from Crowdin for multiple locales for the same language

[john-gom]

What

We only currently support 2-letter language codes but this means that translations for different locales for the same language, such as en-GB and en-AU, get merged back into the same file, causing potential conflicts.

Steps to reproduce the behavior:

1. In Crowdin add a translation for a term in en-GB (English, United Kingdom)
2. See that this creates a PR modifying the messages_en file

Expected behavior

The Crowdin language list should only match languages that we support