KYIV — Lt. Gen. Kyrylo Budanov’s glowering face is barely visible in the half-light of his office. He likes to work in the dark, as befits the chief of Ukraine’s military intelligence service, the GUR. Behind him in the gray gloom, you can see a painting of a giant owl, the symbol of his service, savagely devouring a bat that is the motif of its Russian counterpart.