Demo data for IoT and self-ordering IoT has been reorganized into the dedicated demo area. This keeps sample data separate from regular setup data, reducing confusion during installations and maintenance without changing business features.

Demo data in those modules were in `data/` folder, they are now in the `demo/` one.

Task: 4399091

An obsolete internal marker used in mailing duplicate checks was removed. Duplicate detection now relies on the actual message content, such as the body and attachments, keeping the process simpler without changing the user experience.

This context key is not used anymore. It was used to help determining duplicates in mailing mode. However we now check for the content (body, attachments, ...) which is considered as complete.