Error when watching service endpoints across all namespaces

This was a bug reported by @bketelsen who is using the proxy/config/api source channel.

A watch of service endpoints across all namespaces was throwing an error because it was using the older key method that was missed in an update of the enforce namespace PR.
Prefer if we can deliver this fix now so its consistent with the rest of the areas, and we update how context/namespace is handled per our other issue.