oo-accept-systems: Drop obsolete/downloaded carts

Fix the check_nodes_cartridges test in oo-accept-systems to ignore obsolete
cartridges returned by the node hosts, because the broker will not list
obsolete cartridges, and to ignore downloaded cartridges returned by the by
the broker, because a node will not have downloaded cartridges in its
cartridge repository.

This commit fixes bug 1124938.
oo-accept-systems: Warn about obsolete cartridges

Modify the check_nodes_cartridges test in oo-accept-systems to warn about
obsolete cartridges returned by the node hosts.
Merge pull request #5677 from Miciah/bug-1124938-fix-check_nodes_cartridges-obsolete-and-downloaded-cartridges

Merged by openshift-bot