Schema metadata inferred from collection validators can become stale while a query is executing if a collection’s validator or validation options change during a yield. This change adds CollectionSchemaChecker, which tracks the schema metadata epoch for collection-wide constraints and kills affected plans with QueryPlanKilled when the metadata changes.

The checker is integrated into:

• Classic RequiresCollectionStage restore handling.
• SBE PlanYieldPolicySBE restore handling.
• Plans involving multiple collections.
• Validator, validation-level, and validation-action metadata rebuilds.

Plans only rely on metadata when the validation level is constraint. Relaxing that guarantee also invalidates previously protected plans.