Liberally add "noqa no-changed-when" tags to the problematic tasks,
except for two "systemd-tmpfiles --create" calls. For these we can
simply include the creates= parameter in the command module's call.

ansible-lint 6.5.0 complains about:

  name: All names should start with an
        uppercase letter. (name[casing])

These are used to signal the start of the document in a stream of many
documents. As Ansible only supports one YAML document per file this is
unnecessary. About a third of our YAML documents already lacked these.

roles/archweb: Make archweb install and use it's own memcached service, running as the archweb user and using a socket.