The sleepy East Bay suburbs of Newark, Union City, Castro Valley and Fremont may seem like an unlikely locale for the latest battleground between public transit operators and ride-booking services, such as Uber and Lyft. But it’s here that AC Transit, which operates buses in Alameda and Contra Costa counties, is going bumper-to-bumper with the tech darlings, offering a competing service that blends on-demand rides with traditional bus routes. And, the agency says, it may just be working.