Remove unnecessary assert and value assignment

1) cls.test_data['size'] is not used in test_images.py,
so it can be removed.

2) self.assertIn('port_state', iface) is not needed because
the api schema interface_common_info already checks it

Change-Id: Ibaebb220d73f5d9e7bfdf39a172f70023f193270
diff --git a/tempest/api/compute/servers/test_attach_interfaces.py b/tempest/api/compute/servers/test_attach_interfaces.py
index 9bba733..e0c8887 100644
--- a/tempest/api/compute/servers/test_attach_interfaces.py
+++ b/tempest/api/compute/servers/test_attach_interfaces.py
@@ -79,7 +79,6 @@
 
     def _check_interface(self, iface, port_id=None, network_id=None,
                          fixed_ip=None, mac_addr=None):
-        self.assertIn('port_state', iface)
         if port_id:
             self.assertEqual(iface['port_id'], port_id)
         if network_id:
diff --git a/tempest/api/image/v2/test_images.py b/tempest/api/image/v2/test_images.py
index 56b3517..2812c68 100644
--- a/tempest/api/image/v2/test_images.py
+++ b/tempest/api/image/v2/test_images.py
@@ -164,7 +164,6 @@
         cls.client.store_image_file(image['id'], data=image_file)
         # Keep the data of one test image so it can be used to filter lists
         cls.test_data = image
-        cls.test_data['size'] = size
 
         return image['id']