[Usage billing] Duo Chat attribute both NamespaceId and RootNamespaceId to the default namespace

While testing Duo Chat billing events on staging, we observed that ClickHouse records always attribute both RootNamespaceId and NamespaceId to the default namespace, even when the request originates from a group in a different namespace.

Expected Behavior

• RootNamespaceId should contain the root namespace ID.
• NamespaceId should contain the immediate namespace ID from which the Duo Chat request originated.
• These values should differ when the request is triggered from a subgroup.

Actual Behavior

• Both RootNamespaceId and NamespaceId are populated with the same efault namespace ID.
• This occurs even when Duo Chat is used within a subgroup or project belonging to a different namespace.

Steps to reproduce

• Ask Agentic Chat a question from a group https://staging.gitlab.com/usage-billing-11252025-premium
• Inspect the event data stored in ClickHouse.
• Observe that both NamespaceId and RootNamespaceId equal the default namespace ID.