network: fix TestServerRegisterPeer data race

To prevent logs after the test ends we need to properly shutdown the
server. The problem is likely related to the fact that zap logger writes
 logs after the test ends.

 Close #2973

Signed-off-by: Ekaterina Pavlova <[email protected]>

pkg/network/server.go

@@ -319,6 +319,10 @@ func (s *Server) Shutdown() {
 	}
 	close(s.quit)
 	<-s.relayFin
+
+	if err := s.log.Sync(); err != nil {
+		fmt.Printf("Error flushing server logs: %v\n", err)
+	}
 }
 
 // AddService allows to add a service to be started/stopped by Server.