fix the number of chips per VM for v5litepod-8 (#513)

Author: gcie

src/xpk/core/system_characteristics.py

@@ -1156,7 +1156,7 @@ def get_system_characteristics_by_device_type(
         2,
         'tpu-v5-lite-podslice',
         'ct5lp-hightpu-4t',
-        8,
+        4,
         AcceleratorType['TPU'],
         'v5litepod-8',
     ),