Polish code

test=develop

python/paddle/fluid/framework.py

@@ -2716,11 +2716,6 @@ class Program(object):
         # whether the program is optimized by memory_optimize_transpiler
         self.__is_mem_optimized = False
 
-        # if this program has been optimized by distributed optimizer
-        # fleet_opt will be given a value
-        self._fleet_opt = None
-        self._program_config = None
-
     @property
     def _is_mem_optimized(self):
         # if the program is optimized, operator input/outputs