GUI2/Chatbox: disable chat history

[ci skip]

This prevents private chat logs being saved in your preferences file. History isn't
currently working anyway, and it seems weird to be saving logs this way, especially
since it also records private messages.

data/gui/widget/chatbox.cfg

@@ -168,7 +168,6 @@
 					[text_box]
 						id = "chat_input"
 						definition = "default"
-						history = "mp_chat_input_history"
 					[/text_box]
 				[/column]