For quic loss detection tuning, add a new reward function using average http latency and run it side by side with the existing reward function. protected by --gfe2_reloadable_flag_quic_enable_loss_detection_experiment_at_gfe. PiperOrigin-RevId: 319825747 Change-Id: Ic990510ce43f71990edb1ecc7180b8459e706173