"DNF4 Integration Tests" CI test does not use librepo built from a pull request

[ppisar]

In PR #302 we noticed that "DNF4 Integration Tests" tests a wrong code on a pull request. Instead of installing librepo built from the pull request, it installs librepo from copr:copr.fedorainfracloud.org:rpmsoftwaremanagement:dnf-nightly repository. That repository contains a day old snapshot.

That means the "DNF4 Integration Tests" is never run for a pull request code and completely misses the point of CI.

The same applies to "DNF5 Integration Tests" task.