Upgrade to NixOS 24.05

We need to upgrade our systems to the latest NixOS version 24.05 - release post - to ensure we benefit from the latest features, security patches, and performance improvements. This upgrade is essential for maintaining system stability and security compliance.

The release notes should be read to know what will change or have been added.

This upgrade must be done after 21st of June but can be prepared and tested before. Ensure that the downtime period is well known and has been announced on RNL's website and an email has been sent to all the people who have a virtual machine hosted in RNL.