With merge of commit [1] all calls of clients in Manila
post_test_hook.sh script fail, because used Devstack's file 'openrc'
does not export env var that contains domain name. That became
required after switch to Keystone v3 API in CI jobs [1].
Note: manilaclient calls should have been worked, as default values are
automatically picked up by Keystone server. But such clients as nova
requires set of domain name explicitly.
[1] Ic211a11308a3295409467efd88bff413482ee58d
Change-Id: Ia1976af058164da8ef9e33296006750aab7b3f50
Closes-Bug: #1559456