update example dashboard - prometheus labels had changed

[edaniszewski]

This PR:

• updates the example grafana dashboard for synse server application metrics. these were not updated when the exported metrics had changed.
• adds additional labels to HTTP metrics to make them easier to aggregate

To run:

$ cd examples/monitoring
$ docker-compose up -d

then visit localhost:3000 in your web browser.

The example now has synse-loadgen attached, so if you let it run for a short while, you should see all the stuff populate.

Note due to the additional labels in this PR, you'll need to build this image locally (e.g. make docker) to have everything running happily. The emulator should also be the latest v3 release.

I think all of the charts make sense, but I'd like a second pair of eyes to make sure that the data is being displayed correctly (e.g. the queries do what the charts say they do)

its wip

[edaniszewski]

@lazypower @KylerBurke updated this to be more complete. its a bit of jumping hurdles to test it since you need the right versions of all the images, but if its not too much trouble, could either of you look through and make sure it looks ok and the queries make sense

[lazypower]

I fired up the dash and it looks pretty great.

The GRPC table is a nice touch. Nothing to add from me, good job 👍