Replace tf.contrib.framework.get_or_create_global_step() with...

Replace tf.contrib.framework.get_or_create_global_step() with tf.train.get_or_create_global_step() in third_party/tensorflow_models

See https://www.tensorflow.org/api_docs/python/tf/contrib/framework/get_or_create_global_step and #2795

PiperOrigin-RevId: 176534973

research/adversarial_text/graphs.py

@@ -118,7 +118,7 @@ class VatxtModel(object):
   """
 
   def __init__(self, cl_logits_input_dim=None):
-    self.global_step = tf.contrib.framework.get_or_create_global_step()
+    self.global_step = tf.train.get_or_create_global_step()
     self.vocab_freqs = _get_vocab_freqs()
 
     # Cache VatxtInput objects