Fix: Setting config.default_locale / CONFIG_DEFAULT_LOCALE updates default locale of the site

[tbiering]

Description

This pull requests includes a fix for the non-working configuration option config.default_locale / CONFIG_DEFAULT_LOCALE.
Setting the value now properly applies the locale for any unregistered user visiting the site.
Visiting the site as a registered user still applies the locale set in the user's profile.

The fix has been tested by using configuration value set in the environment variables of the docker-compose.yml

Example for CONFIG_DEFAULT_LOCALE="de"

services:
  thunderdome:
    build:
      context: .
      dockerfile: ./build/Dockerfile
    restart: always
    ports:
      - "8080:8080"
    depends_on:
      - db
    links:
      - db
    networks:
      - asgard
    environment:
      APP_DOMAIN: ".127.0.0.1"
      COOKIE_SECURE: "false"
      # CONFIGURATION FOR TESTING
      CONFIG_DEFAULT_LOCALE: "de"
      # --- CONFIGURATION FOR TESTING
      SMTP_SECURE: "false"
      SMTP_HOST: mail
      SMTP_PORT: 1025
      DB_NAME: thunderdome
      DB_USER: thor
      DB_PASS: odinson
    volumes:
      - ./etc:/etc/thunderdome
[...]

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation Update
• 🎨 Style
• 🧑‍💻 Code Refactor
• 🔥 Performance Improvements
• ✅ Test
• 🤖 Build
• 🔁 CI
• 📦 Chore (Release)
• ⏩ Revert

Related Tickets & Documents

Fixes #577

Screenshots/Recordings

Before fix: before-fix_locale-all

After fix:

• Locale not set (defaults to english): post-fix_locale-default-none
• Locale set to "en": post-fix_locale-default-english
• Locale set to "de": post-fix_locale-default-german

Steps to QA

1. Set environment variable CONFIG_DEFAULT_LOCALE to "de" using configuration in docker-compose.yml (see above)
2. Start up using docker-compose up --build
3. Validate that the preselected language is now german using the language selector button.
4. Parts of the site are now displayed in german - use the "login"-button for reference. It should now be labeled "Anmeldung".
   (Note: Only parts of the translation file are currently translated)

[tbiering]

I just notices that my fix included modifications to an auto-generated file 🤦‍♂️. I will work on the fix and update the PR accordinly.