Ticket 49474 - sasl allow mechs does not operate correctly
Bug Description: In a fix to sasl allowed mechs, the logic
was not properly configured.
Fix Description: Alter the ids_sasl_supported_mech to be
clearer and simpler in it's design.
https://pagure.io/389-ds-base/issue/49474
Author: wibrown
Review by: tbordaz (Thank you!)
Cherry picked from f75cfbce07b79272a7f1a2e387dc232d45c169f5