Remove unused variables ‘LOG'

Perhaps it will be used for debbuging, but now it's unused.

Change-Id: I6017cd862c07d8a4f3702ab5b6209abcf2607fa1

tricircle/db/core.py

@@ -22,14 +22,10 @@ from oslo_config import cfg
 import oslo_db.options as db_options
 import oslo_db.sqlalchemy.session as db_session
 from oslo_db.sqlalchemy import utils as sa_utils
-from oslo_log import log as logging
 from oslo_utils import strutils
 
 from tricircle.common import exceptions
 
-
-LOG = logging.getLogger(__name__)
-
 db_opts = [
     cfg.StrOpt('tricircle_db_connection',
                help='db connection string for tricircle'),