Add service label to revisions

[akyyy]

/area API
/area monitoring
/kind question

Expected Behavior

There is serving.knative.dev/service label in routes and configurations only.

Actual Behavior

The revision pods don't have serving.knative.dev/service label.

Additional Info

If we had this label in revision pods, then we could filter metrics using the service label.

[nader-ziada]

@akyyy the Service name label has been added to the Revision object as part PR #1966 to add environment variables inside the pod, and a conformance test has been added for labels in PR #2039

relevant code here

Please check if these changes resolve your issue. Thanks

[mdemirhan]

@pivotal-nader-ziada The PR addresses this issue - I validated this with the latest HEAD and we get the label correctly into pods. Thanks for the fix & heads up!