switch documentation job to new PTI
switch documentation job to new PTI

This is a mechanically generated patch to switch the documentation
jobs to use the new PTI versions of the jobs as part of the
python3-first goal.

See the python3-first goal document for details:
https://governance.openstack.org/tc/goals/stein/python3-first.html

Change-Id: I69b021f7bcdd7f95487a3747d77b958df5e0e4c5
Story: #2002586
Task: #24286

ChameleonCloud/blazar,ChameleonCloud/blazar,stackforge/blazar,stackforge/blazar,openstack/blazar,openstack/blazar