Remove unused logging import and LOG global var

In some modules the global LOG is not used any more. And the import
of logging is not used. This patch removes the unused logging import
and LOG vars.

Change-Id: I794ee719d76f04e70154cf67f726152fbb1ba15a

watcher/decision_engine/solution/default.py

@@ -16,14 +16,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 #
-from oslo_log import log
-
 from watcher.applier.actions import base as baction
 from watcher.common import exception
 from watcher.decision_engine.solution import base
 
-LOG = log.getLogger(__name__)
-
 
 class DefaultSolution(base.BaseSolution):
     def __init__(self):