We have an arm specific task here to install the HWE kernel. We use
first found to select these tasks which means the default Debian package
setup (unattended upgrades and cleanup) is not installed on our arm
servers.
Fix this by having the arm specific tasks include the generic Debian
tasks.
Change-Id: Ibb57e8b095a4cbd27cc14ef0c5ad45c61edc0679