This issue was fixed before by installing the following fork in the openedx-i18
Docker image: https://github.com/edx/i18n-tools/pull/95

I later removed it, incorrectly assuming that the latest release of
edx-i18n-tools now included the fix. Turns out, no release of edx-i18n-tools
has been made since 0.5.4, in November 2020.

See: https://discuss.overhang.io/t/es-es-does-not-display/1831

Background
==========
As part of our Squad-based ownership, we should stay on top of what
happens in these repositories. However, due to the number of
repositories (and subsequently pull requests) across the edX ecosystem,
it is challenging to stay on top of notifications, separating the
'signal' from the 'noise'. Email filters can go a long way to taming
Inbox notifications, but this is manual and requires maintenance as
Squad ownership changes. It also fails to account for Github-specific behavior.

Proposal
========
By leveraging Github support for `CODEOWNERS` files [1],
we can ensure that our team is at least CCed explicitly, here,
in the form a requested review. This request is just that, a request,
not a requirement; we are not enacting any new merge requirements
at this time.

- [1] https://docs.github.com/en/github/creating-cloning-and-archiving-repositories/about-code-owners

See upstream PR: https://github.com/edx/i18n-tools/pull/95

The credentials are stored in a (non-versioned) transifexrc file which
is mounted in the translation container when downloading the
translations.

See:
https://discuss.overhang.io/t/translate-tutor-in-other-language/1078/4

However there are a couple issues that need to be fixed, so the locale
is disabled for the moment.

We take the opportunity to slightly improve docker image building step.

Here, we build our own docker image instead of using
overhangio/openedx:latest. This avoids a circular dependency, as
overhangio/openedx depends on openedx-i18n.

Also, we upgrade the translations to ironwood.

This reverts commit 64bb8277.