ci/papr: Drop cosa build

It's currently covered by the Jenkins job.

.papr.yml

@@ -15,24 +15,6 @@ tests:
 
 ---
 
-# Build a Fedora CoreOS ostree
-context: fcos-cosa-build
-inherit: true
-
-# This test case wants unprivileged recursive containers
-# which we don't have right now; so just provision a VM and do a
-# docker --privileged run.
-# https://github.com/openshift/origin/issues/21514
-host:
-  distro: fedora/29/atomic
-
-tests:
-  - ./ci/cosa-build.sh
-
-timeout: 120m
-
----
-
 context: f29-primary
 inherit: true