Roll back gfe2_reloadable_flag_quic_can_send_ack_frequency.

This will withdraw the old format of the ACK_FREQUENCY frame from production. Assuming there are no major impacts, we can then roll out the new format.

Protected by FLAGS_quic_reloadable_flag_quic_can_send_ack_frequency.

PiperOrigin-RevId: 713679259

Author: martinduke

quiche/common/quiche_feature_flags_list.h

@@ -19,7 +19,7 @@ QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_probe_two_rounds, true, true,
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_bbr2_simplify_inflight_hi, true, true, "When true, the BBHI copt causes QUIC BBRv2 to use a simpler algorithm for raising inflight_hi in PROBE_UP.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_block_until_settings_received_copt, true, true, "If enabled and a BSUS connection is received, blocks server connections until SETTINGS frame is received.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_buffered_store_set_client_cid, false, true, "If true, QuicBufferedPacketStore will set client CID in packets it generates.")
-QUICHE_FLAG(bool, quiche_reloadable_flag_quic_can_send_ack_frequency, true, true, "If true, ack frequency frame can be sent from server to client.")
+QUICHE_FLAG(bool, quiche_reloadable_flag_quic_can_send_ack_frequency, false, false, "If true, ack frequency frame can be sent from server to client.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_chaos_protector_avoid_copy, false, true, "When true, avoid unnecessary copy in QuicChaosProtector.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_conservative_bursts, false, false, "If true, set burst token to 2 in cwnd bootstrapping experiment.")
 QUICHE_FLAG(bool, quiche_reloadable_flag_quic_conservative_cwnd_and_pacing_gains, false, false, "If true, uses conservative cwnd gain and pacing gain when cwnd gets bootstrapped.")