Follow-up to 9513649679d19b755660d82b5c54ac8ce299b6f3

fix default value for CONF.service_available.barbican to False,
otherwise these tests will be skipped even when barbican tempest plugin
is absent at all.

Change-Id: I844ac1e7f125d65994d7cb5c2eaf7069973804e3
Related-prod: PROD-22487
3 files changed