Update 84-metrics.conf.tmpl

Add environment variable for server-id, when running multiple instances of puppet_server it is quite an issue to identify which c ompiler is which

Author: ChristianTrab

openvoxserver/container-entrypoint.d/84-metrics.conf.tmpl

@@ -2,7 +2,7 @@
 metrics: {
     # a server id that will be used as part of the namespace for metrics produced
     # by this server
-    server-id: localhost
+    server-id: ${HOSTNAME}
     registries: {
         puppetserver: {
             # specify metrics to allow in addition to those in the default list