gfe-relnote: Deprecate gfe2_reloadable_flag_quic_one_immediate_ack.

PiperOrigin-RevId: 299851798
Change-Id: I1a4d177225479737af765c7528c60b8d259b857b

quic/core/quic_received_packet_manager.cc

diff --git a/quic/core/quic_received_packet_manager.cc b/quic/core/quic_received_packet_manager.cc
index 6298dcd..017ae2b 100644
--- a/quic/core/quic_received_packet_manager.cc
+++ b/quic/core/quic_received_packet_manager.cc
@@ -90,9 +90,7 @@
   if (config.HasClientSentConnectionOption(kACKQ, perspective)) {
     fast_ack_after_quiescence_ = true;
   }
-  if (GetQuicReloadableFlag(quic_one_immediate_ack) &&
-      config.HasClientSentConnectionOption(k1ACK, perspective)) {
-    QUIC_RELOADABLE_FLAG_COUNT(quic_one_immediate_ack);
+  if (config.HasClientSentConnectionOption(k1ACK, perspective)) {
     one_immediate_ack_ = true;
   }
 }