Add Python 3 Train unit tests
Add Python 3 Train unit tests

This is a mechanically generated patch to ensure unit testing is in place
for all of the Tested Runtimes for Train.

See the Train python3-updates goal document for details:
https://governance.openstack.org/tc/goals/train/python3-updates.html

Change-Id: I3cb7d2c482cf6d57e01892b6ba0f76d9580ff53c
Story: #2005924
Task: #34216

rahulunair/kolla,stackforge/kolla,stackforge/kolla,openstack/kolla,stackforge/kolla,rahulunair/kolla,openstack/kolla