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Is your feature request related to a problem? Please describe.

The system address book only contains contacts with published or federated properties. Other properties are not written.

Describe the solution you'd like

1. Write local properties too. Write contacts with only local properties. Only discard properties scoped as private.
2. Filter contacts when syncing to federated instances to remove all local properties.

Describe alternatives you've considered

Additional context

#19575 (comment)