Description
Translation files are not related to bundles but to translation domains (see https://github.com/symfony/symfony-docs/pull/9935/files for a recent doc improvement about this).

However, Symfony allows overriding translation files in these 3 ways:

1. <your-project>/translations/
2. <your-project>/src/Resources/<bundle-name>/translations/
3. <bundle-src>/Resources/translations/

1. and 3. look OK, but 2. looks unnecessary because translations are related to domains, not bundles. Should we deprecate it?