Maybe he scheduled the message ahead of time, but it seems that actor Bryan Cranston tweeted a thank you to fans of “Breaking Bad” during the intermission of his Sunday performance of “All the Way” at the American Repertory Theater in Cambridge. At about 2:40 p.m., he tweeted, “Well, this is it. The last episode ever of Breaking Bad. Thank you for sharing this ride with me. Without you we never would have lasted.” (His Sunday performance at the ART started at 1.) Cranston was spotted walking around Cambridge in a Red Sox cap Saturday.