Raises the maximum Ansible version in requirements.txt to Ansible 2.5.x
for both kayobe and kolla ansible.

Also removes the hack to use a patched parted module for ceph block
device management, as Ansible 2.4 contains the required fix.

Change-Id: I0d2f564eb1ddb63b07829d6f0d918af26887db97
Story: 2001649
Task: 6668