Remove obsolet "default()" in template

Author: mhutter

templates/unit.j2

@@ -33,7 +33,7 @@ ExecStart={{ docker_path }} run \
   {{ params('--cap-drop', container_cap_drop) }}\
   {{ params('--device', container_devices) }}\
   {% if container_privileged == true %}--privileged{% endif %}\
-  {{ container_args | default('') | trim }} \
+  {{ container_args | trim }} \
   {{ container_image }} {{ container_cmd | default('') | trim }}
 {% endif %}
 {% if not 'ExecStop' in service_systemd_options_keys %}