Convert docker molecule usage to podman

This change updates all uses of docker to podman and removes our docker
installation process from zuul and our local test process. Some container
based tests have been moved to "delegated" becuase they no longer make
sense to run in a container and the hacks needed to maintain the container
based testing are not worth maintaining for podman.

Change-Id: I02de94a1229bfa847f14ecf282eadbcfe6396875
Signed-off-by: Kevin Carter <kecarter@redhat.com>

_skeleton_role_/molecule/default/molecule.yml

@@ -1,6 +1,6 @@
 ---
 driver:
-  name: docker
+  name: podman
 
 log: true
 
@@ -17,6 +17,8 @@ platforms:
     environment: &env
       http_proxy: "{{ lookup('env', 'http_proxy') }}"
       https_proxy: "{{ lookup('env', 'https_proxy') }}"
+    ulimits: &ulimit
+      - host
 
   - name: centos8
     hostname: centos8
@@ -27,6 +29,7 @@ platforms:
       - /etc/ci/mirror_info.sh:/etc/ci/mirror_info.sh:ro
     environment:
       <<: *env
+    ulimits: *ulimit
 
 provisioner:
   name: ansible