More metrics, more visibility with the new Datadog Agent

The latest version of Datadog's agent (dd-agent 4.0.0) has been released, offering new integrations for PostFix and Couchbase. This release focuses on collecting more metrics from existing integrations to provide users with enhanced visibility into their application stack. A new JMX collector is included in the updated version of the Agent, making it easy to customize metrics from various Datadog integrations. The new Agent also collects additional metrics for NGINX, Postgres, Cassandra, Tomcat, Solr, ActiveMQ, and HAProxy. Additionally, Couchbase integration has been added thanks to contributions from @jslatts.