Description: Mark conflict resolution test cases as 'xfail' (ds49591).
Fix SASL test. Fix Python 3 bytes issues in ds-replcheck tool.
Roll back a part of the PBKDF2_SHA256 schema fix because upgrade fails
without this part of the code.

https://pagure.io/389-ds-base/issue/49761

Reviewed by: vashirov, mreynolds (Thanks!)