Remove reference to battery from auto text

The headunit's battery consumption is negligible on Auto, so it's not a
motivation for the hibernation feature.

UI: https://hsv.googleplex.com/5053486326611968

Bug: 189491742
Test: m GooglePermissionController && adb install && view app
Change-Id: Ifc44e5a38d26005d90edd82a38582d7ec34a9c0d