decrease test data, test=develop (#25252)

python/paddle/fluid/tests/unittests/ctr_dataset_reader.py

@@ -66,10 +66,14 @@ class CtrReader(object):
         pass
 
     def _reader_creator(self, filelist):
+        def get_rand(low=0.0, high=1.0):
+            return random.random()
+
         def reader():
             for file in filelist:
                 with open(file, 'r') as f:
                     for line in f:
+                        if get_rand() < 0.05:
                             fs = line.strip().split('\t')
                             dnn_input = load_dnn_input_record(fs[0])
                             lr_input = load_lr_input_record(fs[1])