Fix a bug in `QuicSession::GetFlowControlSendWindowSize` when the input stream id is a qpack stream id.

Protected by FLAGS_quic_opport_bundle_qpack_decoder_data5 (Replaces v4 flag).

PiperOrigin-RevId: 630643286
diff --git a/quiche/quic/core/quic_connection_test.cc b/quiche/quic/core/quic_connection_test.cc
index b199c6d..7f3208a 100644
--- a/quiche/quic/core/quic_connection_test.cc
+++ b/quiche/quic/core/quic_connection_test.cc
@@ -700,7 +700,7 @@
     EXPECT_CALL(visitor_, OnCongestionWindowChange(_)).Times(AnyNumber());
     EXPECT_CALL(visitor_, OnPacketReceived(_, _, _)).Times(AnyNumber());
     EXPECT_CALL(visitor_, OnSuccessfulVersionNegotiation(_)).Times(AnyNumber());
-    if (GetQuicRestartFlag(quic_opport_bundle_qpack_decoder_data4)) {
+    if (GetQuicRestartFlag(quic_opport_bundle_qpack_decoder_data5)) {
       EXPECT_CALL(visitor_, MaybeBundleOpportunistically()).Times(AnyNumber());
       EXPECT_CALL(visitor_, GetFlowControlSendWindowSize(_)).Times(AnyNumber());
     }