One and one-half stars. Rated PG-13. 105 minutes. The fourth — and least satisfying — collaboration between director Jaume Collet-Serra and Liam Neeson (after “Unknown,” “Non-Stop” and “Run All Night”), “The Commuter” places Neeson’s now-familiar AARP-eligible action hero, this time an insurance salesman and ex-cop named Mike MacCauley, on the 6:25 train home from Manhattan to suburban New York. It’s a day like any other, except that Mike has just been fired.