Prometheus queries from the Telemetry service were taking seconds or 10s
of seconds.
Optimize these queries:
- Move all summary queries requiring a single point data off of Prometheus'
QueryRange() endpoint, onto Query()
- Set `defaultVectorRange` to 30s, and also use it regardless of time
window
Also add tests for grpc_server and telemetry server
Signed-off-by: Andrew Seigner <siggy@buoyant.io>
Fixes#260
Andrew Seigner