[wasm-reduce] Fix time calculation (#7627)

Now that we only run the reduction command once per candidate rather
than twice, we don't need to divide the measured execution time in half.

Author: tlively

src/tools/wasm-reduce.cpp

@@ -196,7 +196,7 @@ struct ProgramResult {
     }
     code = pclose(stream);
     timer.stop();
-    time = timer.getTotal() / 2;
+    time = timer.getTotal();
   }
 #endif // _WIN32