keycloak(host): move to new network and hostname

Also just listen on port 8443 for keycloak-admin proxy protocol.

resources/chaosknoten/keycloak/nginx/invite.hamburg.ccc.de.conf

@@ -4,11 +4,12 @@
 server {
     # Listen on a custom port for the proxy protocol.
     listen 8443 ssl http2 proxy_protocol;
+    listen [::]:8443 ssl http2 proxy_protocol;
     # Make use of the ngx_http_realip_module to set the $remote_addr and
     # $remote_port to the client address and client port, when using proxy
     # protocol.
     # First set our proxy protocol proxy as trusted.
-    set_real_ip_from 172.31.17.140;
+    set_real_ip_from 2a00:14b0:4200:3000:125::1;
     # Then tell the realip_module to get the addreses from the proxy protocol
     # header.
     real_ip_header proxy_protocol;