Add missing @dbtest test-skip rules

[rolandwalker]

Description

Some newish tests lacked the @dbtest decorator which ensures that the test is skipped when a connection is not present.

Checklist

• I added this contribution to the changelog.md file.
• I added my name to the AUTHORS file (or it's already there).
• To lint and format the code, I ran

  uv run ruff check && uv run ruff format && uv run mypy --install-types .