Don't treat manually scheduled cards with no reps as new cards

[user1823]

Complements the change in #3639, ensuring that scheduler and rescheduling produce the same results.

To be more precise, it complements the removal of the following code in #3639

    if !revlogs_complete {
        revlogs_complete = matches!(
            entries.first(),
            Some(RevlogEntry {
                review_kind: RevlogReviewKind::Manual,
                ..
            }) | Some(RevlogEntry {
                review_kind: RevlogReviewKind::Rescheduled,
                ..
            })
        );
    }