Note: this work should be evaluated on top of SERVER-132506 new checks.

checkMetadataConsistency currently treats system.buckets.* namespaces as permitted to have leftover UNTRACKED CSS on non-DB-primary shards (via isNamespacePermittedToHaveUntrackedCssInconsistency). That exception was added alongside temporary-collection swallows, but buckets collections are not in the same category. This ticket tracks removing that swallow and investigating any real leftovers that surface once it is gone.

Why buckets should not be swallowed

• Buckets are legal, durable collections. Viewful timeseries backing collections (system.buckets.<coll>) go through sharding DDL / CreateCollectionCoordinator.
• Placement rules still apply. Untracked timeseries are expected only on the DB primary. Tracked timeseries carry routing metadata like any other tracked collection. UNTRACKED CSS for a buckets nss on a non-DB-primary shard is therefore either a real inconsistency or a CSS-lifecycle bug — not an expected steady state to ignore.
• Temp timeseries paths are already covered. Named helpers already include timeseries temp forms:
  • isOutStageTmpCollection() matches system.buckets.tmp.agg_out.*
  • isRenameCollectionTmpCollection() matches system.buckets.tmp%%%%%.renameCollection
    So legitimate temporary buckets workspaces do not require a blanket isTimeseriesBucketsCollection() exception.