tests: disable tablets in CQL Counter's tests

As tablets don't support counters yet, they need to be disabled in Counter type tests. See https://github.com/scylladb/scylladb/commit/c70f321c6f581357afdf3fd8b4fe8e5c5bb9736e.

Pre-review checklist

[x] I have split my patch into logically separate commits.
[x] All commit messages clearly explain what they change and why.
~~[] I added relevant tests for new features and bug fixes.~~
[x] All commits compile, pass static checks and pass test.
[x] 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.~~