Replace the usage of 'admin_manager' with 'os_admin'

In tempest, alias 'admin_manager' has been moved to 'os_admin'
in version Pike, and it will be removed in version Queens [1].

The other usages which also need to be replaced, are listed below:
* manager > os_primary [2]
* os_adm > os_admin [3]
* os > os_primary [4]

[1] https://review.openstack.org/#/c/467852/
[2] https://review.openstack.org/#/c/468036/
[3] https://review.openstack.org/#/c/467605/
[4] https://review.openstack.org/#/c/466991/

Change-Id: If8880565ba6a70b1b1419394f4706fe37cfff1c4
4 files changed
tree: 04f13675b21261b8b4ad3094e3440943f6cebdcd
  1. manila_tempest_tests/