Fixes issues caused by this merge:
https://github.com/fleetdm/fleet/pull/48261.
- [X] QA'd all new/changed functionality manually
## Summary by CodeRabbit
* **Tests**
* Improved server startup test coverage for health checks to better
reflect how an external client reaches the service.
* Added cleanup to restore network settings after server startup tests,
reducing the chance of one test affecting others.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
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## Summary by CodeRabbit
* **Tests**
* Improved server startup checks to better reflect real external client
behavior during readiness probing.
* Added cleanup so network-blocking settings are restored after test
runs, reducing the chance of one test affecting another.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Lucas Manuel Rodriguez
e719ece82c