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: Ie8da44c2a1360eece2ea47d131af214e9d4dbec8
Story: #2002586
Task: #24292
3 files changed