Deprecate gfe2_restart_flag_dont_fetch_quic_private_keys_from_leto

PiperOrigin-RevId: 397744407
diff --git a/quic/core/crypto/quic_crypto_server_config.cc b/quic/core/crypto/quic_crypto_server_config.cc
index f2a8809..f2efdd8 100644
--- a/quic/core/crypto/quic_crypto_server_config.cc
+++ b/quic/core/crypto/quic_crypto_server_config.cc
@@ -1628,15 +1628,6 @@
   static_assert(sizeof(config->orbit) == kOrbitSize, "incorrect orbit size");
   memcpy(config->orbit, orbit.data(), sizeof(config->orbit));
 
-  if ((kexs_tags.size() != static_cast<size_t>(protobuf.key_size())) &&
-      (!GetQuicRestartFlag(dont_fetch_quic_private_keys_from_leto) &&
-       protobuf.key_size() == 0)) {
-    QUIC_LOG(WARNING) << "Server config has " << kexs_tags.size()
-                      << " key exchange methods configured, but "
-                      << protobuf.key_size() << " private keys";
-    return nullptr;
-  }
-
   QuicTagVector proof_demand_tags;
   if (msg->GetTaglist(kPDMD, &proof_demand_tags) == QUIC_NO_ERROR) {
     for (QuicTag tag : proof_demand_tags) {
diff --git a/quic/core/quic_flags_list.h b/quic/core/quic_flags_list.h
index daad95a..9abf6d9 100644
--- a/quic/core/quic_flags_list.h
+++ b/quic/core/quic_flags_list.h
@@ -6,8 +6,6 @@
 
 #ifdef QUIC_FLAG
 
-QUIC_FLAG(FLAGS_quic_restart_flag_dont_fetch_quic_private_keys_from_leto, true)
-
 QUIC_FLAG(FLAGS_quic_restart_flag_quic_offload_pacing_to_usps2, false)
 // A testonly reloadable flag that will always default to false.
 QUIC_FLAG(FLAGS_quic_reloadable_flag_quic_testonly_default_false, false)