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: Ide7c4b796c480666bf514e5a31476a7a087b39d3
Story: #2002586
Task: #24294

openstack/dragonflow,openstack/dragonflow,openstack/dragonflow