Cover the case when the container engine is not available.

In the case the container engine passed in tripleo_container_cli
isn't installed (for example: if we try to remove a docker container
when the instance has podman installed and docker isn't present) then
the role would fail. This patch includes a guard which in the case
the container engine passed in tripleo_container_cli doesn't exist
then nothing is done.
Besides, a check for the container being run in the docker-rm part
was missing, this check is being added too.

Change-Id: Ib5501321fef1a3921fbb17bcfabfb2f5c7c96c41
Related-Bug: #1836531

tripleo_ansible/roles/tripleo-container-rm/tasks/main.yml

@@ -15,7 +15,13 @@
 # under the License.
 
 
+- name: Check for {{ tripleo_container_cli }} cli
+  command: "command -v {{ tripleo_container_cli }}"
+  register: check_container_cli
+  failed_when: false
+
 - include_tasks: "tripleo_{{ tripleo_container_cli }}_container_rm.yml"
   vars:
     container: "{{ item }}"
   with_items: "{{ tripleo_containers_to_rm }}"
+  when: check_container_cli.rc == 0

tripleo_ansible/roles/tripleo-container-rm/tasks/tripleo_docker_container_rm.yml

@@ -14,8 +14,14 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+- name: "Check if {{ container }} is running in docker backend"
+  command: "docker inspect --type container --format exists {{ container }}"
+  register: stat_docker_container
+  failed_when: false
 
 - name: remove "{{ container }}" container
   docker_container:
     name: "{{ container }}"
     state: absent
+  when:
+    - stat_docker_container.rc == 0