Add network configuration and DNS settings for various hosts

- Created a new configuration file for ga-al-gw-neu with detailed network interface settings and routing rules.
- Updated existing configurations for ga-al-gw, ga-gh-gw, ga-nh-gw, ga-st-gw-ersatz, ga-st-gw, and ga-st-mail to include additional DNS servers and correct domain controller IPs.
- Disabled systemd-resolved for ga-st-mail to prevent conflicts with DNS settings.
- Added user definitions and SSH key configurations for default users across multiple hosts.

host_vars/ga-gh-gw.oopen.de/ga-gh-gw-common.yml

@@ -200,8 +200,12 @@ systemd_resolved: true
 #    IPv6: 2001:678:ed0:f000::
 #    Servername für DNS-over-TLS: dot.ffmuc.net
 #    für iOS 14+: DoT-Server-Konfiguration (unsigniert, vom PrHdb)
+# Note: systemd-resolved uses 'FallbackDNS' only if no 'DNS' is configured at all. So
+#       the other (internal) nameserver gateways are listed here as additional DNS servers.
 resolved_nameserver:
   - 127.0.0.1
+  - 192.168.11.1
+  - 192.168.10.1
 
 # search domains
 #
@@ -219,7 +223,8 @@ resolved_dnssec: false
 # dns.as250.net: 194.150.168.168
 #
 resolved_fallback_nameserver:
-  - 194.150.168.168
+  - 192.168.11.1
+  - 192.168.10.1
 
 
 # ---
@@ -339,7 +344,7 @@ bind9_gateway_acl:
       - '# Nameserver Gateway Stockhausen'
       - 192.168.11.1
       - '# Domain Controller Stockhausen'
-      - 192.168.10.3
+      - 192.168.11.3
       - '# Nameserver Gateway Altenschlirf'
       - 192.168.10.1
       - '# Domain Controller Altenschlirf'