cloud: rework package list, add comments
This reworks the package list to add comments and remove some things
that didn't need to be explicitly removed.
- remove +systemd-udev -> already included by default
- remove -biosdevname -> not included by default
- remove -iprutils -> not included by default
- remove -uboot-tools -> not included by default
There are no packages added or removed from the built cloud image as
part of this change. Just updating the input package list to be more
meaningful.