Fix: [Network] clients leaving because of broken connections was not broadcasted (#9238)

The code mixed up "client has quit but we already told everyone"
with "client lost connection, handle this".

Split up those two signals:
- CLIENT_QUIT means we told everyone and the connection is now dead
- CONNECTION_LIST means we should tell everyone we lost a client

src/network/core/tcp_admin.cpp

@@ -41,7 +41,7 @@ NetworkAdminSocketHandler::~NetworkAdminSocketHandler()
 NetworkRecvStatus NetworkAdminSocketHandler::CloseConnection(bool error)
 {
 	delete this;
-	return NETWORK_RECV_STATUS_CONN_LOST;
+	return NETWORK_RECV_STATUS_CLIENT_QUIT;
 }
 
 /**