When a hot backup captures a snapshot during an FCV upgrade, the restored node can end up with legacy system.buckets collections at FCV 8.3.

This happens because oplog replay re-creates collections using the OFCV from the oplog entry ("upgrading from 8.0 to 8.3"), but the _finalizeUpgrade work (upgradeAllTimeseriesToViewless) is never replayed. The validate_collections_on_shutdown hook then calls listIndexes directly on the system.buckets namespace, which is blocked by featureFlagBlockDirectSystemBucketsAccess at FCV 8.3, causing error 491.

To fix this, we will skip system.buckets collections from the listIndexes consistency check when the flag is enabled.