ReshardingTxnCloner will return true from its until() lambda when the cancellation token isn't canceled. This means the remote donor shard returning a Cancellation or NotPrimary error causes the local recipient shard to halt cloning config.transactions records. The !cancelToken.isCanceled() condition should really be cancelToken.isCanceled() (see also ReshardingCollectionCloner for comparison).

if (status.isA<ErrorCategory::CancellationError>() ||
    status.isA<ErrorCategory::NotPrimaryError>()) {
    // Cancellation and NotPrimary errors indicate the primary-only service Instance
    // will be shut down or is shutting down now - provided the cancelToken is also
    // canceled. Otherwise, the errors may have originated from a remote response rather
    // than the shard itself.
    //
    // Don't retry when primary-only service Instance is shutting down.
    return !cancelToken.isCanceled();
}

This pattern with AsyncTry is fairly common throughout the resharding code. We should consider making a common utility to express this logic. The withAutomaticRetry() function added as part of SERVER-51606 switched to a pattern that avoids checking the cancellation token in the until() lambda because the AsyncTry always checks the cancellation token on its own anyway.