Increase initial flow control limit in MASQUE toy code

Since this toy code doesn't properly implement flow control, this change allows receiving larger message bodies.

PiperOrigin-RevId: 737291544

quiche/quic/masque/masque_h2_connection.cc

diff --git a/quiche/quic/masque/masque_h2_connection.cc b/quiche/quic/masque/masque_h2_connection.cc
index 9931887..2feaa2c 100644
--- a/quiche/quic/masque/masque_h2_connection.cc
+++ b/quiche/quic/masque/masque_h2_connection.cc
@@ -68,7 +68,7 @@
   settings.push_back(
       Http2Setting{Http2KnownSettingsId::MAX_CONCURRENT_STREAMS, 100});
   settings.push_back(
-      Http2Setting{Http2KnownSettingsId::INITIAL_WINDOW_SIZE, 65535});
+      Http2Setting{Http2KnownSettingsId::INITIAL_WINDOW_SIZE, 268435456});
   settings.push_back(Http2Setting{Http2KnownSettingsId::MAX_FRAME_SIZE, 16384});
   settings.push_back(
       Http2Setting{Http2KnownSettingsId::MAX_HEADER_LIST_SIZE, 65535});