Peet’s Coffee, which opened an elaborate kiosk at Westfield Montgomery in the summer of 2015, has gone dark after failing to steal much business away from Starbucks. Peet’s, which has only a handful of stores in Montgomery County, was hampered at the mall by its out-of-the-way location in the Sears wing. Its former kiosk is temporarily serving as a weekend pop-up shop for Rumi Tea & Spice.