taskotron/resultsdb-backend: the stg and prod certificates are named differently

The certificates are resultsdb.crt in prod while they are resultsdb.stg.crt in
staging so by using the ansible variable {{ env_suffix }} we're able to support
both files in one line.

Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>

roles/taskotron/resultsdb-backend/tasks/main.yml

@@ -70,12 +70,12 @@
     group: "{{ item.group }}"
     mode: "{{ item.mode }}"
   with_items:
-    - src: "{{private}}/files/rabbitmq/{{env}}/pki/issued/resultsdb.crt"
+    - src: "{{private}}/files/rabbitmq/{{env}}/pki/issued/resultsdb{{ env_suffix }}.crt"
       dest: resultsdb.crt
       owner: root
       group: apache
       mode: 0644
-    - src: "{{private}}/files/rabbitmq/{{env}}/pki/issued/resultsdb.key"
+    - src: "{{private}}/files/rabbitmq/{{env}}/pki/issued/resultsdb{{ env_suffix }}.key"
       dest: resultsdb.key
       owner: root
       group: apache