Discard the pre-lock test namespace anchors before launch

What

A few test namespaces in staging and production carry a decimal Rails id in the owner anchor entity_id, predating the provisioning rule that admits only the organization's canonical UUIDv7. No customer rows exist yet, so these can be deleted rather than migrated.

While they exist: the namespace details endpoint's organization comparison can never match them, and their usage events land in unattributed_events_total (census predicate in docs/dev/usage-data.md).

Tasks

• Delete the staging and production test namespaces whose anchor entity_id is not a canonical UUIDv7.
• Once zero rows remain, revisit the deliberately absent sampled log line paired with unattributed_events_total: with the known population gone, a per-namespace line becomes pure regression signal.

Related to #670 (closed)