storage: remove deprecated database_connection

This option is not used currently and was already deprecated in
Ceilometer Kilo – it's therefore safe to remove it now.

Change-Id: I7706f7a162fdfd686c9fce472a216e534e883418

aodh/opts.py

@@ -45,7 +45,6 @@ def list_opts():
              aodh.notifier.rest.OPTS,
              aodh.service.OPTS,
              aodh.rpc.OPTS,
-             aodh.storage.OLD_OPTS,
              aodh.api.controllers.v2.alarms.ALARM_API_OPTS,
              aodh.storage.CLI_OPTS)),
         ('api',

aodh/storage/__init__.py

@@ -28,12 +28,6 @@ _NAMESPACE = 'aodh.storage'
 
 LOG = log.getLogger(__name__)
 
-OLD_OPTS = [
-    cfg.StrOpt('database_connection',
-               secret=True,
-               help='DEPRECATED - Database connection string.',
-               ),
-]
 
 OPTS = [
     cfg.IntOpt('alarm_history_time_to_live',