gfe-relnote: (n/a) Remove QuicStreamSequencerBuffer::GapsDebugString(). No behavior change, not protected. This function is not doing what its name suggests, we don't really need it because (in logs) we can always use bytes_received_ to infer gaps. Also fixed some clang-tidy issues. PiperOrigin-RevId: 294281430 Change-Id: Idce0b55b3f7c06adf80b97f169460fe669624ac0