[functions] Added default metrics for Prometheus (#5885)

Currently functions do not report the default Prometheus metrics
like the broker does, or any JMX metrics that normally get
reported by kafka clients.

This add the default Prometheus exports used by the broker as
well as JMX exports that are reported by kafka clients when
using the kafka wrapper.

This change is a trivial rework / code cleanup without any test coverage.
diff --git a/distribution/server/src/assemble/LICENSE.bin.txt b/distribution/server/src/assemble/LICENSE.bin.txt
index 470d05c..a091bd3 100644
--- a/distribution/server/src/assemble/LICENSE.bin.txt
+++ b/distribution/server/src/assemble/LICENSE.bin.txt
@@ -371,6 +371,7 @@
     - io.prometheus-simpleclient_servlet-0.5.0.jar
     - io.prometheus-simpleclient_log4j2-0.5.0.jar
     - io.prometheus-simpleclient_jetty-0.5.0.jar
+    - io.prometheus.jmx-collector-0.12.0.jar
     - io.prometheus-simpleclient_caffeine-0.5.0.jar
  * Bean Validation API -- javax.validation-validation-api-1.1.0.Final.jar
  * Log4J