gfe-relnote: In QUIC, remove QuicStream::set_fin_received while move QuicStream::set_fin_sent to protected (renamed to SetFinSent and this should only be used by Google QUIC). No functional change expected, not protected. PiperOrigin-RevId: 306913013 Change-Id: I4d962f3f7527511f424a0a7767fdea009b8f9766