Geo: In-progress repository syncs should not count as failed

Currently, while a repository is syncing, the relevant Geo::ProjectRegistry has resync_wiki: true or resync_wiki: true. The failed scope depends on this value to count a repository as failed, so in-progress repositories that have never failed are counted as failed.

We should be able to add a requirement like where(failure_count: 0) to the failed scope to avoid this. It's really off-putting in the UI when you've just set up a Geo node and it says things are failing immediately, when in fact they're progressing nicely.