Ticket 49137 - Add sasl plain test - ds
    
    Bug Description:  We should check that SASL plain works correctly
    
    Fix Description:  We add a test that verifies that SASL plain only
    works with a TLS connection, that it works with correct and incorrect
    passwords.
    
    https://pagure.io/389-ds-base/issue/49137
    
    Author: wibrown
    
    Review by: mreynolds (Thanks!)