MD7 - Curtin preseeds are deprecated

Since Remove
3.8.0 TBD

This notice is raised as a warning of the deprecation of Curtin preseeds in a future release.

MAAS is transitioning away from Curtin preseeds, which will result in the removal of preseed-based customisation.

Curtin preseeds have been used to apply low-level installation customisations during machine deployment. These configurations allowed users to modify storage layouts, run custom installation commands, and tailor deployment behaviour to specific environments. With the upcoming changes, this mechanism will be replaced by Deployment scripts.

Documentation and guidance for using Deployment scripts will be provided once the new mechanism is available. At that time, we will share more information to help users migrate their existing Curtin preseed customisations.