Silicon Valley companies may be going all in on artificial intelligence, but Bay Area residents are broadly concerned about the technology – including many of the tech workers riding the wave.That’s according to a poll of Bay Area locals this summer by the Mercury News and Joint Venture Silicon Valley, a nonprofit think tank. Only 28% of respondents from around the region said they expect AI to have a positive impact on their own lives over the next two decades. Even fewer – 18% – said the technology will have a positive impact on society in that time. A slim…