remove the default setting that unables GPUs in the job node

parl/remote/job.py

@@ -16,7 +16,6 @@
 import compatible_trick
 
 import os
-os.environ['CUDA_VISIBLE_DEVICES'] = ''
 os.environ['XPARL'] = 'True'
 import argparse
 import cloudpickle

parl/remote/tests/paddle_gpu_test.py

@@ -29,7 +29,6 @@ import os
 @parl.remote_class
 class Actor(object):
     def __init__(self):
-        os.environ['CUDA_VISIBLE_DEVICES'] = "0"
         if parl.utils.is_gpu_available():
             place = fluid.CUDAPlace(0)
         else: