Remove systemd version + ostree check for docker TasksMax (#11493)

systemd ignores unknown keys (with a warning) so version checking is not
necessary.
There is no rationale for excluding it from ostree systems either.

roles/container-engine/docker/templates/docker.service.j2

@@ -31,9 +31,7 @@ ExecStart={{ docker_bin_dir }}/dockerd \
           $DOCKER_OPTS \
           $DOCKER_STORAGE_OPTIONS \
           $DOCKER_DNS_OPTIONS
-{% if not is_ostree and systemd_version.stdout|int >= 226 %}
 TasksMax=infinity
-{% endif %}
 LimitNOFILE=1048576
 LimitNPROC=1048576
 LimitCORE=infinity