Move proposal job into project-config
Move proposal job into project-config

Change Iac9054de55728601d839c1feede15c2a5acc45b6 made the
propose-updates job protected, meaning it can only be defined in the
project-config repo.  Move it to there

Change-Id: Id839ac69ed44553a8d2d88547b2c54502af4a913
Needed-By: https://review.opendev.org/678135

openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals,openstack/openstack-manuals