Draw strength counts opponents without confirmed results

[czlee]

It's not clear to me what the behaviour should be, just something I noticed when writing unit tests.

If there is a debate with only unconfirmed ballots, then this debate doesn't count towards the second-order metrics used in calculating draw strength, but the fact that it is drawn does count for the purposes of determining who a team's opponents have been when calculating draw strength. This is arguably a strange inconsistency—we are counting their opponents' record in a team's draw strength, even when it isn't fully accounted for that they faced the opponent.

For now, I've marked these as expected failures in 78ca17f.