chore: remove useless option

It seems the conductor_life_check_timeout option is not used in
the code entirely.  We can just remove it at this point.

Change-Id: Ie07ede20f55593041319b3a52de8fca9f3b9514b

Author: mnaser

magnum/conf/conductor.py

@@ -20,10 +20,6 @@
     cfg.StrOpt('topic',
                default='magnum-conductor',
                help='The queue to add conductor tasks to.'),
-    cfg.IntOpt('conductor_life_check_timeout',
-               default=4,
-               help=('RPC timeout for the conductor liveness check that is '
-                     'used for cluster locking.')),
     cfg.IntOpt('workers',
                help='Number of magnum-conductor processes to fork and run. '
                     'Default to number of CPUs on the host.')