How to speed up OSP13 minor update

Issue

• A minor update of OSP13 is slow, because ansible-playbook is extremely slow due to amount of fact data gathered across the entire cloud.
• An update of compute nodes took so long time(for example, an update of 30 compute nodes took 11.5 hours) with the latest OSP13 z release.
• According to package_update.log under /var/log/mistral/, ansible took 1 minutes or more every skipped task.