Resolves#45220 (one of several PRs)
- [x] QA'd all new/changed functionality manually
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## Summary by CodeRabbit
* **Tests**
* Added a dedicated maintained-apps test helper and updated integration
tests to use it, consolidating sync test setup and improving reliability
of maintained-apps scenarios.
* Updated several tests to use improved test utilities and helper
variants for SQL test helpers and request fixtures.
* **Chores**
* Adjusted CI lint checks to exclude the new test helper location from
specific env-var override validations.
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[](https://app.coderabbit.ai/change-stack/fleetdm/fleet/pull/45494)
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