Do not include index etc. in DROPSONDE origin

So the metric name is the same across VMs. This makes it easier to create a single graph for a metric, split-up by VM

[#76563270]
Revert "Point metron agents at cf etcd to discover loggregator"

This reverts commit 47326a34f253dfdc7ed232d66b530b1ba2f8244f.