Shared-pool tenants were instance admins of the whole instance (fixed, unreleased)

What this changes for operators

• PR #7525 (merged to master 2026-06-12, NOT in a tagged release) removes a grant that made every cloud tenant on a shared pool an instance admin with reach into every other tenant's data, and purges stale admin rows. Shared-pool operators must track the next tag and provision a non-cloud-tenant admin identity first (the purge is destructive).