Fixes#30574.
# Checklist for submitter
If some of the following don't apply, delete the relevant line.
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product design team. -->
- [x] Changes file added for user-visible changes in `changes/`,
`orbit/changes/` or `ee/fleetd-chrome/changes`.
See [Changes
files](https://github.com/fleetdm/fleet/blob/main/docs/Contributing/guides/committing-changes.md#changes-files)
for more information.
- [x] Input data is properly validated, `SELECT *` is avoided, SQL
injection is prevented (using placeholders for values in statements)
- [x] Added/updated automated tests
- [x] Manual QA for all new/changed functionality
<!-- This is an auto-generated comment: release notes by coderabbit.ai
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## Summary by CodeRabbit
* **Bug Fixes**
* Resolved issues with recording host certificate sources when multiple
hosts share the same certificate but have different usernames, improving
accuracy and performance.
* Addressed related performance and database load problems for these
scenarios.
* **Tests**
* Added new tests to ensure certificate source records remain properly
isolated per host, even when certificates are shared across hosts.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->
Ian Littman
d78a76010e