Merge the release into the backup health work and read the real dump health

The readiness model now takes the database dump's state from
getDatabaseBackupHealth, and the dump test reaches the off-host key id
where it moved.

src/lib/data-wipe/wipe-plan.ts

@@ -359,6 +359,8 @@ export const INSTANCE_SCOPED: Readonly<Record<string, string>> = {
     "per backup signal, what the admins were last told; a fact about the instance's backups, not about any account",
   RecoveryKitConfirmation:
     "the instance's recovery kit confirmation (key ids and fingerprints); the confirming admin is a plain id, not a relation",
+  DatabaseBackupRun:
+    "the instance's ledger of nightly whole-database dumps; describes the server, not any account",
   OffhostPurgeRequest:
     "the deletions an account deletion or wipe asked of the off-host bucket; written by the wipe itself and removed once the bucket holds nothing of the account",
   CycleSymptomCategory: