Fix issue where OHTTP client hangs if the TLS/TCP handshake fails

Prior to this change, the connection pool would try to fail the pending request before it was added, causing it to stay pending forever.

PiperOrigin-RevId: 864281542

quiche/quic/masque/masque_connection_pool.cc

diff --git a/quiche/quic/masque/masque_connection_pool.cc b/quiche/quic/masque/masque_connection_pool.cc
index 3dd3b9b..50fd485 100644
--- a/quiche/quic/masque/masque_connection_pool.cc
+++ b/quiche/quic/masque/masque_connection_pool.cc
@@ -410,9 +410,9 @@
       // `SSL_set_bio` causes `ssl_` to take ownership of `bio`.
       connection_ = std::make_unique<MasqueH2Connection>(
           ssl_.get(), /*is_server=*/false, connection_pool_);
-      connection_->OnTransportReadable();
       connection_pool_->AttachConnectionToPendingRequests(authority_,
                                                           connection_.get());
+      connection_->OnTransportReadable();
     }
     connection_->AttemptToSend();
   }