Remove oss/ent_scylla_version params from xfail_scylla_version_lt

[sylwiaszunejko]

xfail_scylla_version_lt now takes a single scylla_version parameter instead of separate oss_scylla_version and ent_scylla_version params. The enterprise/OSS version branching logic is removed; the decorator simply compares the current version against the single provided version.

Update all call sites accordingly.

Pre-review checklist

• I have split my patch into logically separate commits.
• All commit messages clearly explain what they change and why.
• I added relevant tests for new features and bug fixes.
• All commits compile, pass static checks and pass test.
• PR description sums up the changes and reasons why they should be introduced.
• I have provided docstrings for the public items that I want to introduce.
• I have adjusted the documentation in ./docs/source/.
• I added appropriate Fixes: annotations to PR description.