flatten inventories making them simpler

Remove the child groups as we weren't using their functionality anyway.
Also remove the debian_11/12 host groups as they're not in use.

inventories/chaosknoten/hosts.yaml

@@ -1,6 +1,4 @@
 all:
-  children:
-    debian_12:
   hosts:
     ccchoir:
       ansible_host: ccchoir-intern.hamburg.ccc.de
@@ -59,7 +57,7 @@ all:
       ansible_host: zammad-intern.hamburg.ccc.de
       ansible_user: chaos
       ansible_ssh_common_args: -J ssh://chaos@public-reverse-proxy.hamburg.ccc.de
-    base_config_hosts:
+base_config_hosts:
   hosts:
     ccchoir:
     cloud:
@@ -76,7 +74,7 @@ all:
     tickets:
     wiki:
     zammad:
-    docker_compose_hosts:
+docker_compose_hosts:
   hosts:
     ccchoir:
     grafana:
@@ -87,10 +85,10 @@ all:
     pad:
     pretalx:
     zammad:
-    nextcloud_hosts:
+nextcloud_hosts:
   hosts:
     cloud:
-    nginx_hosts:
+nginx_hosts:
   hosts:
     ccchoir:
     eh22-wiki:
@@ -106,10 +104,10 @@ all:
     public-reverse-proxy:
     wiki:
     zammad:
-    public_reverse_proxy_hosts:
+public_reverse_proxy_hosts:
   hosts:
     public-reverse-proxy:
-    certbot_hosts:
+certbot_hosts:
   hosts:
     ccchoir:
     eh22-wiki:
@@ -124,7 +122,7 @@ all:
     pretalx:
     wiki:
     zammad:
-    prometheus_node_exporter_hosts:
+prometheus_node_exporter_hosts:
   hosts:
     ccchoir:
     eh22-wiki:
@@ -136,7 +134,7 @@ all:
     pretalx:
     wiki:
     zammad:
-    infrastructure_authorized_keys_hosts:
+infrastructure_authorized_keys_hosts:
   hosts:
     ccchoir:
     eh22-wiki:
@@ -151,10 +149,10 @@ all:
     public-reverse-proxy:
     wiki:
     zammad:
-    wiki_hosts:
+wiki_hosts:
   hosts:
     eh22-wiki:
     wiki:
-    netbox_hosts:
+netbox_hosts:
   hosts:
     netbox:

inventories/z9/hosts.yaml

@@ -1,6 +1,4 @@
 all:
-  children:
-    debian_11:
   hosts:
     light:
       ansible_host: light.z9.ccchh.net
@@ -8,18 +6,16 @@ all:
     authoritative-dns:
       ansible_host: authoritative-dns.z9.ccchh.net
       ansible_user: chaos
-    debian_12:
+nginx_hosts:
-      hosts:
-    nginx_hosts:
   hosts:
     light:
-    ola_hosts:
+ola_hosts:
   hosts:
     light:
-    foobazdmx_hosts:
+foobazdmx_hosts:
   hosts:
     light:
-    infrastructure_authorized_keys_hosts:
+infrastructure_authorized_keys_hosts:
   hosts:
     light:
     authoritative-dns: