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_packet_creator.h b/quic/core/quic_packet_creator.h
index ea93552..85e0091 100644
--- a/quic/core/quic_packet_creator.h
+++ b/quic/core/quic_packet_creator.h
@@ -32,8 +32,9 @@
       : public QuicConnectionCloseDelegateInterface {
    public:
     ~DelegateInterface() override {}
-    // Get a buffer of kMaxPacketSize bytes to serialize the next packet.
-    // If return nullptr, QuicPacketCreator will serialize on a stack buffer.
+    // Get a buffer of kMaxOutgoingPacketSize bytes to serialize the next
+    // packet. If return nullptr, QuicPacketCreator will serialize on a stack
+    // buffer.
     virtual char* GetPacketBuffer() = 0;
     // Called when a packet is serialized. Delegate does not take the ownership
     // of |serialized_packet|, but takes ownership of any frames it removes