Roll back gfe2_restart_flag_quic_gfe_ecn_sockets. Leave it enabled in canary for debug purposes.

Blocked by b/276786878.

PiperOrigin-RevId: 521806120

quiche/quic/core/quic_flags_list.h

diff --git a/quiche/quic/core/quic_flags_list.h b/quiche/quic/core/quic_flags_list.h
index 12a1bc1..cebbbff 100644
--- a/quiche/quic/core/quic_flags_list.h
+++ b/quiche/quic/core/quic_flags_list.h
@@ -91,8 +91,6 @@
 QUIC_FLAG(quic_reloadable_flag_quic_default_to_bbr, false)
 // When true, quiche UDP sockets report Explicit Congestion Notification (ECN) [RFC3168, RFC9330] results.
 QUIC_FLAG(quic_restart_flag_quic_quiche_ecn_sockets, true)
-// When true, report received ECN markings to the peer on GFE sockets.
-QUIC_FLAG(quic_restart_flag_quic_gfe_ecn_sockets, true)
 // When true, report received ECN markings to the peer.
 QUIC_FLAG(quic_restart_flag_quic_receive_ecn, true)
 // When true, support draft-ietf-quic-v2-08