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/http/quic_spdy_session_test.cc b/quic/core/http/quic_spdy_session_test.cc
index 190c0ed..e6e7f57 100644
--- a/quic/core/http/quic_spdy_session_test.cc
+++ b/quic/core/http/quic_spdy_session_test.cc
@@ -703,7 +703,7 @@
 
   EXPECT_CALL(*send_algorithm, CanSend(_)).WillRepeatedly(Return(true));
   EXPECT_CALL(*send_algorithm, GetCongestionWindow())
-      .WillRepeatedly(Return(kMaxPacketSize * 10));
+      .WillRepeatedly(Return(kMaxOutgoingPacketSize * 10));
   EXPECT_CALL(*send_algorithm, InRecovery()).WillRepeatedly(Return(false));
   EXPECT_CALL(*stream2, OnCanWrite()).WillOnce(Invoke([this, stream2]() {
     session_.SendStreamData(stream2);