Rename quic::kMaxPacketSize to quic::kMaxOutgoingPacketSize

As part of cl/242197597, QUIC now has separate values for maximum incoming and outgoing packet sizes. This CL renames the constant to be clearer.

gfe-relnote: constant rename, no functional impact
PiperOrigin-RevId: 242708648
Change-Id: I3f440ba44b9c12394026116aaecdd2c166cc63b6
diff --git a/quic/core/quic_stream_test.cc b/quic/core/quic_stream_test.cc
index 87f1d6e..e154482 100644
--- a/quic/core/quic_stream_test.cc
+++ b/quic/core/quic_stream_test.cc
@@ -72,7 +72,7 @@
 class QuicStreamTestBase : public QuicTestWithParam<ParsedQuicVersion> {
  public:
   QuicStreamTestBase()
-      : initial_flow_control_window_bytes_(kMaxPacketSize),
+      : initial_flow_control_window_bytes_(kMaxOutgoingPacketSize),
         zero_(QuicTime::Delta::Zero()),
         supported_versions_(AllSupportedVersions()) {}