Remove QuicDispatcher::set_new_session_allowed_per_event_loop(). This is a private method, so whoever has access to it (like QuicDispatcherPeer) has access to the private member new_session_allowed_per_event_loop_ directly. gfe-relnote: n/a, no fuctional change. PiperOrigin-RevId: 279743685 Change-Id: I5a744209601cf5cf1857d29ac868e8ffd9a436ab