installer: verify if adding docker repo breaks customer environments with apt proxy

[tpurschke]

try to avoid adding docker.list

    - name: add docker repo
      lineinfile:
        path: "/etc/apt/sources.list.d/docker.list"
        regexp: ".*https://download.docker.com/linux/.*"
        create: true
        line: "deb [arch=amd64] https://download.docker.com/linux/{{ ansible_distribution | lower }} {{ os_codename }} stable"