Cirrus: Upd. ext. service check host list
Since CI doesn't depend heavily on installing packages at runtime
(there is some minor use) there's no need to exhaustively check
repository mirror hosts.  Remove them from the list.
@@ -2,13 +2,3 @@ github.com 22
docker.io 443
quay.io 443
registry.fedoraproject.org 443
-mirrors.fedoraproject.org 443
-dl.fedoraproject.org 443
-ewr.edge.kernel.org 443
-mirror.clarkson.edu 443
-mirror.umd.edu 443
-mirror.vcu.edu 443
-mirrors.cat.pdx.edu 443
-pubmirror1.math.uh.edu 443
-pubmirror2.math.uh.edu 443
-sjc.edge.kernel.org 443
