tests: enable vector integration tests on Scylla 2025.4+

[mykaul]

Vector type is supported on Scylla 2025.4 and above. Enable the integration tests.

Tested locally against both 2025.4.2 and 2026.1 and they pass.
Tested locally against 2025.1, where it is skipped, as it should be.

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.

[mykaul]

I'm pretty sure CI is broken :-/