Remove stale legacy yum docker repo /etc/yum.repos.d/docker.repo (#5569)

* Remove stale legacy yum docker repo /etc/yum.repos.d/docker.repo

* move task 'Remove legacy docker repo file' to pre-upgrade.yml

roles/container-engine/docker/tasks/pre-upgrade.yml

 ---
+- name: Remove legacy docker repo file
+  file:
+    path: "{{ yum_repo_dir }}/docker.repo"
+    state: absent
+  when:
+    - ansible_distribution in ["CentOS","RedHat","OracleLinux"]
+    - not is_atomic
+
 - name: Ensure old versions of Docker are not installed. | Debian
   apt:
     name: '{{ docker_remove_packages_apt }}'