queue-proxy not sending some tags on metrics when using opencensus

[jasonaliyetti]

What version of Knative?

0.25.0

Expected Behavior

Opencensus telemetry from the queue-proxy should include configuration_name, revision_name, service_name tags as documented.

Actual Behavior

When I follow the documented setup for OpenTelemetry Collector and export the metrics using a prometheus exporter, the resulting timeseries do not include these expected labels.

Steps to Reproduce the Problem

• Setup knative-serving to use opencensus for request metrics
• Send a request and wait for the metric to show up in otel collector's prometheus exporter endpoint
• Observe on the prometheus exporter endpoint that these labels are missing.

I would note that I am only using opencensus for the request metrics, but I wouldn't expect that to impact this:

metrics.backend-destination: prometheus
metrics.request-metrics-backend-destination: opencensus