Remove migrated utils code

This commit removes all the utils code which has been migrated to
tempest-lib and updates the uses of it to point to the library instead.

Change-Id: I9207641aa91c0ea7feb8e067316fc220880c3a3b
diff --git a/tempest/api/network/test_routers.py b/tempest/api/network/test_routers.py
index 1388b3b..e9c9484 100644
--- a/tempest/api/network/test_routers.py
+++ b/tempest/api/network/test_routers.py
@@ -14,10 +14,10 @@
 #    under the License.
 
 import netaddr
+from tempest_lib.common.utils import data_utils
 
 from tempest.api.network import base_routers as base
 from tempest import clients
-from tempest.common.utils import data_utils
 from tempest import config
 from tempest import test