Add fallback to use 'templates-sdk' when no templates specified and the build is targeting devsite. This is necessary for google3 builds so they can stop referencing copied versions of the template files, because it's too messy to export all the template files into a location they can directly reference for the 'templatesdir' argument. So instead, they now just leave off that argument in their doclava command. am: 11d94c6b46
am: b357c32d70

Change-Id: Id80fb159f45ed13e26a8a4912fac83f76be5fdd0