[Task] Remove unnecessary Checkov suppressions and document remaining ones

### Description

Review the repository for existing Checkov suppressions, particularly those related to NSG warnings, as these issues seem to have been addressed. Remove any Checkov suppressions that are no longer needed. For any suppressions that must remain, clearly document:

- The reason each suppression is still required
- Guidance on what steps would be necessary to harden the resource or remove the warning in the future

This will help ensure the codebase remains secure and maintainable, and that any deviations from best practices are well-justified and actionable.

You can validate if suppressions are still needed by running script `azd-hooks/scripts/hooks/preprovision/run_checkov.ps1` and seeing if checkov fails without it.

### Definition of Done

```markdown
- suppressions removed
- checkov scan succeeded
- remaining suppressions documented with comments,
- comments say how to harden and link to security considerations doc
- remaining suppressions are documented in security considerations
```

### Values Provided

More secure solution.