Prior to this commit, all peer services were transmitted as connect-enabled
as long as a one or more mesh-gateways were healthy. With this change, there
is now a difference between typical services and connect services transmitted
via peering.
A service will be reported as "connect-enabled" as long as any of these
conditions are met:
1. a connect-proxy sidecar is registered for the service name.
2. a connect-native instance of the service is registered.
3. a service resolver / splitter / router is registered for the service name.
4. a terminating gateway has registered the service.
