[Security] refactor LXC Cron Updater

[CrazyWolf13]

📌 Task summary

Remove dynamic pulling from the web and improve security

📋 Task details

This has been a long standing pain point, which we finally want to adress and improve security.

Problem:
On every scheduled run we retrieves and executes the remote code at runtime. While this ensures the latest version is always used, it introduces potential security and supply-chain risks, since the executed code is neither pinned to a specific version nor verified before execution.

Goal:
Improve the current approach, possibly by using some sort of local approach with update func?