MADISON, Wis. — Thousands of Wisconsin union workers rallied at the Capitol on Saturday to protest a “right-to-work” proposal that would outlaw the mandatory payment of union dues. But the crowd was much smaller than those in 2011 against Gov. Scott Walker’s law stripping public sector unions of much of their power. Speakers at the event jeered Walker’s comment Thursday that fighting against protesters during the 2011 debates prepared him to battle terrorists as president.