zammad(host): move to latest upstream compose file version (v14.1.1)

It hopefully fixes bugs we had in the past, so removing the workarounds
and it also comes with default values now, so removing all variables set
to those defaults.

resources/chaosknoten/zammad/docker_compose/compose.yaml

@@ -1,6 +1,11 @@
 ---
 version: "3.8"
 
+# Taken from: https://github.com/zammad/zammad-docker-compose/blob/master/docker-compose.yml
+# Version: v14.1.1
+# Update from new tag by replacing all content.
+# Configuration should be done in the .env.j2.
+
 x-shared:
   zammad-service: &zammad-service
     environment: &zammad-environment