Ensure that queue-proxy can only report statistics for its own Pod

## Expected Behavior

The queue proxy can't report request / concurrency statistics for a Pod other than itself.

## Actual Behavior

(Unknown)

## Steps to Reproduce the Problem

Inspect code and verify that when autoscaler calls the queue proxy, all the statistics from the queue-proxy are associated with the Revision and Pod associated with the queue proxy.

## Additional Info
