IPA: Use search timeout, not enum timeout for searching overrides
    
    Related:
        https://fedorahosted.org/sssd/ticket/2866
    
    If the LDAP connection is still established when the client moves
    offline, we rely on the search timeout to find out the client is
    offline. The override search used the enum timeout defaults to 60 seconds.
    That caused too long delays in going offline.
    
    Reviewed-by: Sumit Bose <sbose@redhat.com>
    (cherry picked from commit a687f4473bf305bc2ccb075cd93154c9d661b638)
    (cherry picked from commit e4231dff16f7b6ff9ef68718a67ea01cec62bab6)