tripleo_container_*/molecule: pull fedora instead of centos8

In these tests, we use the fedora container and not centos:8; so right
after when we run "podman run", it can fail if the fedora image isn't
pulled.

Let's pull the right image before the podman run.

Change-Id: If32d5f9e3ff1a590d2fc467969404861ec733f9b

tripleo_ansible/roles/tripleo-container-rm/molecule/default/prepare.yml

@@ -58,7 +58,7 @@
 
     - name: pull an image
       docker_image:
-        name: centos:8
+        name: fedora
         source: pull
       vars:
         ansible_python_interpreter: "{{ ansible_user_dir }}/test-python/bin/python"
@@ -66,7 +66,7 @@
     - name: Create a data container
       docker_container:
         name: "{{ item }}"
-        image: centos:8
+        image: fedora
         detach: true
         command: sleep 1d
       with_items:

tripleo_ansible/roles/tripleo-container-rm/molecule/legacy_vars/prepare.yml

@@ -32,10 +32,10 @@
         state: latest
 
     - name: Pull container image
-      command: "podman pull centos:8"
+      command: "podman pull fedora"
 
     - name: Create test containers
-      command: "podman run -itd --systemd --name {{ item }} fedora bash"
+      command: "podman run -itd --name {{ item }} fedora bash"
       with_items:
         - podman-legacy-container1
         - podman-legacy-container2

tripleo_ansible/roles/tripleo-container-rm/molecule/podman-rm-stopped/prepare.yml

@@ -32,10 +32,10 @@
         state: latest
 
     - name: Pull container image
-      command: "podman pull centos:8"
+      command: "podman pull fedora"
 
     - name: Create test containers
-      command: "podman run -itd --systemd --name {{ item }} fedora bash"
+      command: "podman run -itd --name {{ item }} fedora bash"
       with_items:
         - podman-container1
         - podman-container2

tripleo_ansible/roles/tripleo-container-rm/molecule/podman/prepare.yml

@@ -32,10 +32,10 @@
         state: latest
 
     - name: Pull container image
-      command: "podman pull centos:8"
+      command: "podman pull fedora"
 
     - name: Create test containers
-      command: "podman run -itd --systemd --name {{ item }} fedora bash"
+      command: "podman run -itd --name {{ item }} fedora bash"
       with_items:
         - podman-container1
         - podman-container2