Use mkosi dependencies in default image

Use mkosi dependencies in default image

Let's reduce duplication by using mkosi dependencies to install
all required dependencies to build the default image. To make this
work we add support for tools trees on jammy/bookworm. We also drop
support for a focal default image as it's too much of a burden to
maintain.

We also remove the EPEL only packages from the CentOS tools tree so
that mkosi dependencies works on a CentOS Stream system without EPEL
enabled.

Finally, curl-minimal is replaced by curl because trying to install
curl-minimal on a system with curl leads to a dnf failure so we opt
for the larger curl in order to make mkosi dependencies useful in
more situations.