This failpoint is error-prone. It is very hard to use it correctly because we check the conditions for the failpoint in TenantCollectionCloner::insertDocumentsCallback. But multiple calls of TenantCollectionCloner::insertDocumentsCallback for different batches could run in parallel because it's scheduled on an executor. So there could be races when using this failpoint together with a small collectionClonerBatchSize because the check for the failpoint's conditions may not align with the batch boundaries.

I think we can delete this failpoint but use tenantMigrationHangCollectionClonerAfterHandlingBatchResponse instead.