Flaky run counts now count only failing runs, not every run in a flaky group

Cross-run flaky detection now marks only the non-reproducing failure as flaky. A passing run that proves the same test case can succeed on the same commit and scheme is no longer counted as flaky. This fixes inflated flaky_run_count, flakiness_rate, and auto-quarantine thresholds that could trigger from a single retried flaky commit. Flaky-group views still display the full pass/fail breakdown for the commit by fetching the complete run history while identifying the flaky group from the failing runs.