TESTS: Tests for sdap_search_initgr_user_in_batch
    
    This patch provides tests for core logic of
    sdap_search_initgr_user_in_batch() function. This function replaces
    old approach with sysdb_try_to_find_expected_dn() function.
    
    Resolves:
    https://fedorahosted.org/sssd/ticket/3230
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Sumit Bose <sbose@redhat.com>