Fix breadcrumb for foundational agent at Project and Group level

What does this MR do and why?

Fix breadcrumb for foundational agent at Project and Group level

NOTE: This is behind the :ai_catalog_synthetic_foundational_items feature flag

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable the new ai_catalog_synthetic_foundational_items flag
2. Visit a foundational agent at the project level:
   • http://gdk.test:8080/gitlab-duo/test/-/automate/foundational_agents/support_assistant/
3. Click on Agent in the breadcrumb
4. The user should be redirected to the agents list page of project (as of now, foundational agents are not yet displayed in the agents list)

MR acceptance checklist

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Related to #599494 (closed)