BF-38639 found that storageInterface->findById() will return EBUSY if the oplogApplier thread is trying to access the oplogTruncateAfterPoint document while another thread is concurrently running validate on local.replset.oplogTruncateAfterPoint, which will trigger this fassert. To prevent this from happening, we need to add concurrency control to make sure the replication layer is aware of when validate is running and exclude access to this table when it is.