Cannot load ECA status page for non-open PRs for GH

When running some final tests before the ECA switchover tomorrow, an issue was found where the status page would fail to load for some requests. This was due to a mix of things, including the random GH timeouts, and no true handling of the non-open cases which is something we want to continue to support.

To fix this, we will remove proactive processing of commits for pull request status requests when there are results, and leave it to Github automatically requesting updates, our fallbacks, and the revalidate button. This should provide good coverage and keep the status up to date in most cases.