...based on f37, not f31. And make it fedora-minimal so it's
smaller. And clean up dnf so it's even smaller. And tag it
with our proper YMD tag, and commit the script that builds it.
This broke the system-df tests. In the process of resolving
that, I found those tests a little lacking. So, improve their
coverage a little bit.
Signed-off-by: Ed Santiago <santiago@redhat.com>
