make "auto_add_missing_translations" work in prod

[DamienVS]

In this page : /blob/master/symfony/auto-add-missing.rst

There's a workaround to make "auto_add_missing_translations" working in prod.

However, in symfony 4.2 that workaround does not work in any config file (that I am aware of) and breaks the config.

Note that everything work well in DEV with the profiler enabled.

My env :
-ubuntu

• php 7.2
• symfony 4.2.*
• "symfony/translation": "4.2.*",
• "php-translation/symfony-bundle": "^0.8.1",