gfe-relnote: For QUIC BBRv2 flows, cut inflight_hi gradually when there is high loss from PROBE_UP. Protected by --gfe2_reloadable_flag_quic_bbr2_cut_inflight_hi_gradually. I'm using CODE_COUNT instead of FLAG_COUNT, in order to observe the effect outside of canary GFEs. PiperOrigin-RevId: 286277020 Change-Id: I55a321981bbccfc47e57426ce765a35320f708ef