Update ansible before the ansible upgrade tasks

Update ansible before the ansible upgrade tasks

In case an ansible update is available during the upgrade then
the ansible package gets updated to a new version by the ansible
tasks. This could potentially lead to issues as the one described
in LP#1729546. This change updates the ansible package via yum
before starting the ansible upgrade tasks in order to avoid having
ansible updating itself.

Related-bug: 1729546

Change-Id: I2ea0aa1f670053578996018663c9fa52dec14b77
(cherry picked from commit 0c1ac1d752aaf88832b34e165f7d147e2304ff1c)