Stop using deprecated tempest options
Stop using deprecated tempest options

With the merge of 'Deprecate credential config options' in tempest,
(Change-Id: Ia5132c5cb32355d6f26b8acdd92a0e55a2c19f41)
admin credentials options have been moved from [identity] group to
[auth] group in tempest/config.py. This makes no difference for cinder
tempest tests.  However manila has separate tempest tests and
in manila_tempest_tests/tests/api/base.py, BaseSharesAdminTest always
gets admin credentials from identity group. It will fail with the
changed configuration options.

Closes-Bug: #1504052
Change-Id: If329a6563df2028a18c3fedea53065688e75339e

openstack/manila,bswartz/manila,bswartz/manila,scality/manila,openstack/manila,vponomaryov/manila,NetApp/manila,NetApp/manila,scality/manila,vponomaryov/manila