Update specs to use fast_spec_helper - Clickhouse

What does this MR do and why?

This MR updates specs in the Clickhouse area to use fast_spec_helper instead of spec_helper where possible, improving test performance by avoiding unnecessary Rails environment loading.

I tested running each changed spec file individually successfully.

References

Related to #581686 (closed)

This MR is part of a broader initiative to convert all specs that can be run with fast_spec_helper across the codebase (~230 files). Using fast_spec_helper significantly reduces test execution time by not loading the full Rails environment when it's not needed.

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