Usually, this test is used for gating ltrace. In such case the
Fedora infrastructure offers the SRPM along with other ltrace
subrpms within a repo called "test-artifacts".
However, this test is also used to test dejagnu, because ltrace
has dejagnu based testsuite. In such case the "test-artifacts"
repo has dejagnu, but not ltrace.
We need to be able to get the ltrace SRPM in both cases.
"koji download-build" is a wrong tool to download artifacts being
tested. They are freshly scratch-built and hosted in a local repo
called "test-artifacts" unknown to koji. Using "dnf download"
directly and limited to that specific repo is a correct way to
reach them.
I'm adding a fallback using the repo's local files just in case
"dnf" suffers some temporary hiccup.
Note: In RHEL, it's "testsuite2" outside of categories, here I'm adding
it to the Sanity category.
Note: I've filed https://bugzilla.redhat.com/show_bug.cgi?id=1963110
and included it as a known failure to make this test pass.
