mkosi: Ensure we build all features/components in mkosi

mkosi: Ensure we build all features/components in mkosi

Explicitly enable all features/components in the mkosi build to
ensure they all get built and we get an error if they can't be built.

We also rework the packages sections of all mkosi configs to reduce
duplication and cover all the dependencies necessary to build/use all
systemd features.

Note that for the final image, since systemd is installed by default
in base images, we rely on that to install the base library dependencies
and we only list extra optional dependencies and tools that aren't already
installed by default into the base image.

We also drop the centos stream 8 mkosi build as dependencies on that
distro are too out-of-date to be able to build all systemd features.
Since centos stream 9 has been out for a while, let's focus on that
and leave it to downstream to keep systemd building on centos stream 8.

Finally, there's a few additions to the mkosi scripts to make sure
services don't start by default on boot.