Kimi Raikkonen says his test run this week onboard Trackhouse Racing’s prototype Cup car was “very beneficial”, insisting his preparations for his NASCAR debut have gone as well as they could. Raikkonen, who retired from Formula 1 at the end of last season, with make his racing return next at Watkins Glen in a round of the NASCAR Cup Series thanks to Trackhouse racing which has entrusted its #91 entry to the Finn. It will be the Finn’s second NASCAR experience, having enjoyed a one-off in the Xfinity Series with Kyle Busch Motorsports during his sabbatical year from F1 in…