kernelci build of cip8 runs out of disk space

Issue Background

If the latest (cip8) tag is checked out then the kernelci build fails

Issue description

The build uses 1.7G which is towards the limit of available space on the VM. The known issues has already been changed to suggest that /home may need enlargement as a higher priority than /var (though depends upon usage.

Acceptance criteria

The disk space on the VM should be adjusted upwards.