Use whitenoise for static file handling (#6662)

* Update config_template.yaml file

* Adjust ALLOWED_HOSTS behaviour

- Only add wildcard * in DEBUG mode
- Exit if ALLOWED_HOSTS not defined

* Tweak error message

* Use whitenoise for serving static files

- Any requests to /static/ are handled by whitenoise
- If an external reverse proxy (e.g. Caddy) is being used, this will not make a difference

* Update python package requirements

* Add extra log output

* Update ENV for CI checks

* Updates

- Thow error but do not exit
- Revert CI changes

requirements.in

@@ -51,6 +51,7 @@ sentry-sdk                              # Error reporting (optional)
 setuptools                              # Standard dependency
 tablib[xls,xlsx,yaml]                   # Support for XLS and XLSX formats
 weasyprint                              # PDF generation
+whitenoise                              # Enhanced static file serving
 
 # OpenTelemetry dependencies
 grpcio