Simplify (and fix) list of strings

uwsgi-python/templates/apps/protokollsystem.j2

@@ -39,9 +39,7 @@ URL_PARAMS = ""
 {% if cdn_url is defined %}
 CDN_URL = "{{cdn_url}}"
 {% endif %}
-{% if protokolle_metadata_domain_whitelist is defined %}
-PERMITTED_METADATA_DOMAINS = [ {{protokolle_metadata_domain_whitelist|map('quote')|join(', ')}} ]
-{% endif %}
+PERMITTED_METADATA_DOMAINS = {{protokolle_metadata_domain_whitelist|default([])}}
 
 PRINTING_ACTIVE = {{ protokolle_printing }}
 PRINTING_SERVER = "{{ protokolle_printing_server }}"