logstash: Disable legacy monitoring data collection

Deprecated since 7.9.0, removed in 8.0.0.

https://www.elastic.co/guide/en/logstash/current/monitoring-internal-collection-legacy.html

README.md

@@ -190,8 +190,7 @@ users][builtin-users] instead for increased security.
 
 1. Replace usernames and passwords in configuration files
 
-    Use the `kibana_system` user inside the Kibana configuration file (`kibana/config/kibana.yml`) and the
-    `logstash_system` user inside the Logstash configuration file (`logstash/config/logstash.yml`) in place of the
+    Use the `kibana_system` user inside the Kibana configuration file (`kibana/config/kibana.yml`) in place of the
     existing `elastic` user.
 
     Replace the password for the `elastic` user inside the Logstash pipeline file (`logstash/pipeline/logstash.conf`).

logstash/config/logstash.yml

@@ -3,10 +3,3 @@
 ## https://github.com/elastic/logstash/blob/master/docker/data/logstash/config/logstash-full.yml
 #
 http.host: "0.0.0.0"
-xpack.monitoring.elasticsearch.hosts: [ "http://elasticsearch:9200" ]
-
-## X-Pack security credentials
-#
-xpack.monitoring.enabled: true
-xpack.monitoring.elasticsearch.username: elastic
-xpack.monitoring.elasticsearch.password: changeme