[APPS-1313][PUB] Remove translation of API responses

:koala: :+1:

This PR removes the translation of strings coming from the BigCommerce API.

### TODO

- [x] Remove the translation code.
- [x] Remove the strings from the translation files.
- [x] @maximeprades confirm we still translate dates to the current user's locale.

### References

* JIRA: https://zendesk.atlassian.net/browse/APPS-1313