Use data_utils in tempest.lib.common.utils

Tempest tests should use the stable method defined in tempest.lib.
This patch is to use data_utils from tempest.lib.common.utils in
OAUTHConsumersV3Test and HACKING.rst.

Change-Id: Ia9f4cf37d8d57da34864a5eb55a8fe9d9c5722f5
2 files changed