LDAP: unlink ccname_file_dummy if there is an error
    
    https://fedorahosted.org/sssd/ticket/2592
    
    If there is an error after ccname_file_dummy is created but before it is
    renamed then the file isn't removed.  This can cause a lot of files to be
    created and take up inodes in a filesystem.
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Sumit Bose <sbose@redhat.com>