Alwas use pathless docker mirror URI

It seems that we need the pathless docker mirror URI for distro docker
now, too, so set it unconditionally.

Change-Id: Ic6918312ec60efba0397b85ee16d91c6393ee90b

roles/install-docker/tasks/mirror.yaml

@@ -4,22 +4,13 @@
     state: directory
     path: /etc/docker
 
-- name: Set docker_mirror fact for upstream docker
+- name: Set docker_mirror fact
   when:
     - docker_mirror is not defined
     - mirror_fqdn is defined
-    - use_upstream_docker
   set_fact:
     docker_mirror: "http://{{ mirror_fqdn }}:8082"
 
-- name: Set docker_mirror fact for distro docker
-  when:
-    - docker_mirror is not defined
-    - mirror_fqdn is defined
-    - not use_upstream_docker
-  set_fact:
-    docker_mirror: "http://{{ mirror_fqdn }}:8081/registry-1.docker/"
-
 - name: Install dockerhub proxy configuration
   become: yes
   when: