Remove remote media compatibility mode. (#8044)

The fallback code shouldn't be needed and is a remnant of the GET
method that old media servers use. Clients using it are likely
to just waste bandwidth and having to download the media again
through the normal transfer from server method. The most reliable
method is to get all missing textures therefore from the server
directly and not spam the remote media server with 404s.

src/client/clientmedia.h

@@ -92,7 +92,6 @@ private:
 	struct RemoteServerStatus {
 		std::string baseurl;
 		s32 active_count;
-		bool request_by_filename;
 	};
 
 	void initialStep(Client *client);