Use centos-8 stream for molecule jobs

Set containers module to 3.0.
Mount dnf vars for evaluating $stream var.
Set --no-stream for ubi container images.
Mark 2 jobs unvoting to fix later.

Change-Id: Ib69f8b5931e846ca012bee8a2bc24dc2a614e274
(cherry picked from commit 8f9a141bf9)

tripleo_ansible/roles/tripleo_persist/molecule/default/molecule.yml

@@ -16,6 +16,7 @@ platforms:
       - /etc/ci/mirror_info.sh:/etc/ci/mirror_info.sh:ro
       - /etc/pki/rpm-gpg:/etc/pki/rpm-gpg
       - /opt/yum.repos.d:/etc/yum.repos.d:rw
+      - /etc/dnf/vars:/etc/dnf/vars
     privileged: true
     environment: &env
       http_proxy: "{{ lookup('env', 'http_proxy') }}"