oslo.log deprecate config option verbose since aug 1, 2015 in review:
in https://review.openstack.org/#/c/206437/
That was a long time ago so it should be possible to remove it now. This
was already merged once but had to be reverted because some projects
were still relying on it. Oslo team plan to remove it, so we need clean
up its usage before removing it.
Closes-Bug: #1663570
Change-Id: I072e1078486f50cebea92695ff46c1af879eb23d