[ambient/multicluster] Don't require to mark waypoints as global explicitly #58064
Description
Describe the feature request
Basically currently in ambient multi-network mode we have to mark services as global to "share" them between networks - that's reasonable to expect user of Istio to mark services that they want to be global explicitly.
If a service has a waypoint, for ambient multi-network to work we would need to tag the waypoint service as global together with the service. It's not a big deal, but ideally we would not need to do that and marking the service as global should be enough.
Affected product area (please put an X in all that apply)
[x] Ambient
[ ] Docs
[ ] Dual Stack
[ ] Installation
[ ] Networking
[ ] Performance and Scalability
[ ] Extensions and Telemetry
[ ] Security
[ ] Test and Release
[ ] User Experience
[ ] Developer Infrastructure
Affected features (please put an X in all that apply)
[x] Multi Cluster
[ ] Virtual Machine
[ ] Multi Control Plane
Additional context
This is related to #57710 and there has been some discussion there about it.