[Bug]: Broken locales not caught by CI

[diox]

Is there an existing issue for this?

• I have searched the existing issues

What happened?

Despite calling make compile_locales in test_needs_locales job (and when building production image) these errors do not bubble up and cause the build/CI to fail:

locale/es_CL/LC_MESSAGES/django.po
Error: E201: invalid variables: {complemento}

locale/tr/LC_MESSAGES/django.po
Error: E201: invalid variables: {version}

locale/cs/LC_MESSAGES/django.po
Error: E201: invalid variables: %(jméno_autora)s

They can be seen when running dennis-cmd lint --errorsonly on the relevant po files, which are currently broken (as of mozilla/addons-server@1b58b5b)

What did you expect to happen?

CI should break until we have fixed these.

┆Issue is synchronized with this Jira Task

[flodolo]

Had to extend our linter, because it's not designed to cover placeholders like {foo}
cs, es-CL: mozilla/addons-server@6dbc7d5
markup errors: mozilla/addons-server@2cb01d4
other placeholder issues: mozilla/addons-server@2e54029

One Ukrainian string I fixed was 11 years old, so not sure the linter ever stopped them 🤔

[diox]

The part that worries me is that the ones I found generate an error locally when running dennis so should have been caught by our CI. The fact that they weren't indicates there is something that regressed here, likely a while ago when we switched to GitHub Actions.