Fix unit test failures
Fix unit test failures

In unit tests, if the config option is accessed before
the config file is loaded results in
oslo_config.cfg.NoSuchOptError. So, It's a safe check to do
if attribute exists before accessing it.

Change-Id: I42fe1dcc5b556c5cab8fda9b38354b86d7ecc1e8

openstack/congress,ramineni/my_congress,ramineni/my_congress,openstack/congress,ramineni/my_congress,ramineni/my_congress