[Regression] Clients aren't updated when waypoints are deleted

[oznogon]

Steps to reproduce

1. Launch EE as a server into a scenario.
2. Launch EE as a client and connect to the server.
3. Join a ship on the server and client and select Relay on both.
4. Place a waypoint in either EE instance.
5. Delete a waypoint in either EE instance.

Expected behavior

The waypoint is deleted on both the server and client.

Observed behavior

The waypoint is deleted on the server, but remains visible in the client. The deleted waypoint remains visible until another waypoint is added by either the server or client, or until the client disconnects and reconnects to the server.