Update NetMessage to pass in MemoryStream (#21796)

Content.Shared/Chat/MsgChatMessage.cs

@@ -57,7 +57,8 @@ namespace Content.Shared.Chat
         public override void ReadFromBuffer(NetIncomingMessage buffer, IRobustSerializer serializer)
         {
             var length = buffer.ReadVariableInt32();
-            using var stream = buffer.ReadAlignedMemory(length);
+            using var stream = new MemoryStream(length);
+            buffer.ReadAlignedMemory(stream, length);
             serializer.DeserializeDirect(stream, out Message);
         }