Scripts for 2 distinct purposes are being mixed in the ci directory

[colin-nolan]

The ci directory started life as a library of scripts for setting up HGI's systems. These scripts are used extensively in our image building repositories.

Now, the ci also contains scripts for the CD of our systems by means of Terraform and GitLab runners. Unlike the previous type of scripts, these are not designed for use outside of hgi-systems.

The ugliest thing about having this increasingly incohesive set of scripts is with the before scripts: the image builders are now sourcing Terraform specific variables.