Both ccache and linux-image-generic were being installed by
install-packages rather than using a package-installs.yaml.
Change-Id: Ib54c5b51d605278bb9d046a897be989c17c6fb0f
As with the previous similar changes, this is intended to catch
problems as they happen instead of ignoring them and continuing on
to potentially fail later. Setting this on all existing scripts
will allow us to enforce use via Jenkins.
Change-Id: Iad2d490c86dceab148ea9ab08f457c49a5d5352e
