CCBC-404: Don't use lcb_list_delete to remove cinfo

If the conninfo structure is in idle state, use
clist_delete so that the ll_idle count will also be decremented.

Change-Id: Idb4f0ea3da332fa3854834ee54e4975b7b1af3c5
Reviewed-on: http://review.couchbase.org/36601
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Dave Rigby <daver@couchbase.com>