Make prometheus-node-exporter not overlap with Synapse metrics port

This was causing a port conflict when `matrix_nginx_proxy_enabled: false`.

Fixes https://github.com/spantaleev/matrix-docker-ansible-deploy/issues/983

group_vars/matrix_servers

@@ -1677,7 +1677,7 @@ matrix_prometheus_node_exporter_enabled: false
 # Normally, matrix-nginx-proxy is enabled and nginx can reach Prometheus Node Exporter over the container network.
 # If matrix-nginx-proxy is not enabled, or you otherwise have a need for it, you can expose
 # Prometheus' HTTP port to the local host.
-matrix_prometheus_node_exporter_container_http_host_bind_port: "{{ '' if matrix_nginx_proxy_enabled else '127.0.0.1:9100' }}"
+matrix_prometheus_node_exporter_container_http_host_bind_port: "{{ '' if matrix_nginx_proxy_enabled else '127.0.0.1:9200' }}"
 
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