The inject code detects the object it is being injected into, and writes
self-identifying information into the CONDUIT_PROMETHEUS_LABELS
environment variable, so that conduit-proxy may read this information
and report it to Prometheus at collection time.
This change puts the self-identifying information directly into
Kubernetes labels, which Prometheus already collects, removing the need
for conduit-proxy to be aware of this information. The resulting label
in Prometheus is recorded in the form `k8s_deployment`.
Signed-off-by: Andrew Seigner <siggy@buoyant.io>