ci: More fixes for cosa build

Use --entrypoint and also rename it while we're here.

Closes: #1889
Approved by: rfairley

.papr.yml

@@ -27,7 +27,7 @@ host:
   distro: fedora/29/atomic
 
 tests:
-  - ./ci/f29-cosa-build.sh
+  - ./ci/cosa-build.sh
 
 timeout: 120m
 

ci/cosa-build.sh

@@ -7,10 +7,11 @@ cosaimg=quay.io/coreos-assembler/coreos-assembler:latest
 podman pull "${cosaimg}"
 
 # Build rpm-ostree using cosa as a buildroot, and extract the result
-podman run --privileged --rm \
+podman run --security-opt label=disable --rm \
        -v $(pwd):/srv/code -w /srv/code \
+       --entrypoint bash --user root \
        "${cosaimg}" \
-       /bin/sh -c './ci/build.sh && make install DESTDIR=$(pwd)/installroot'
+       -c 'yum -y swap fedora-release-container fedora-release && ./ci/build.sh && make install DESTDIR=$(pwd)/installroot'
 
 codedir=$(pwd)
 mkdir fcos