refactor: Allow admins and instance owners to use any credentials in their workflows

[krynble]

Summary

With the introduction of projects within RBAC we broke part of the functionality which is about allowing instance owners and admins to use any credentials within their workflows.

This PR fixes this.

Related tickets and issues

https://linear.app/n8n/issue/PAY-1581

Review / Merge checklist

• [ ] PR title and summary are descriptive. Remember, the title automatically goes into the changelog. Use (no-changelog) otherwise. (conventions)
• [ ] Docs updated or follow-up ticket created.
• [ ] Tests included.