ZAPORIZHZHIA, Ukraine — Clambering over boulders, past old tires and shellfish-encrusted scrap metal, Oleksandr Shkalikov ventured onto the dry bed of a vast reservoir. Out in this wasteland rested a haunting reminder of long-ago battles on this same swath of southern Ukraine: a swastika, chipped into a rock, had emerged from the receding water. The year “1942’’ was written next to it. “History is repeating itself,” Shkalikov, a tank driver on leave from the Ukrainian army, said of the World War