Replace the usage of 'manager' with 'os_primary'

In tempest, alias 'manager' has been moved to 'os_primary'
in version Pike, and it will be removed in version Queens.
This patch is to replace the usage of 'manager' with 'os_primary'.

For other details, please check [1] and [2]
[1] https://review.openstack.org/#/c/468036/
[2] https://review.openstack.org/#/c/463484/

Change-Id: I522405288452f42824991e9709eec4e57aab2606
1 file changed