Enable Logstash's Beats input by default

The configuration from the official Docker image includes it by default:
https://github.com/elastic/logstash/blob/7.9/docker/data/logstash/pipeline/default.conf

More information about the Beats input plugin:
https://www.elastic.co/guide/en/logstash/current/plugins-inputs-beats.html

docker-compose.yml

@@ -41,6 +41,7 @@ services:
         target: /usr/share/logstash/pipeline
         read_only: true
     ports:
+      - "5044:5044"
       - "5000:5000/tcp"
       - "5000:5000/udp"
       - "9600:9600"