[2021] Disable christmas items

I'm sorry for your loss. Unfortunatlely we do not have a time-based event system in place yet, hence the holiday decoration will be gone with Update 9.2 to be released in January. For future events we'll be having a time based change that does not require an update and I'll bring up a possibility to disable holiday themes client-side, though this might not be entirely possible.

I know, but as we want to have event-based items instead of just skins that probably won't be possible.