Race-detector CI runs (-race) slow goroutines enough that a
prior sweeper goroutine (e.g. TestStartSweeper_TransientErrorDoesNotCrashLoop)
can still be running and incrementing pendingUploadsSweepErrors after
metricDelta() captures its baseline, but before the success-path sweeper
records its success metrics. The test then reads deltaError=1 instead of 0.
Fix: add waitForMetricDelta(t, deltaError, 0, 2*time.Second) before the
assertion, matching the polling pattern already used in the error-path
test (TestStartSweeper_RecordsMetricsOnError). This ensures the error
counter has settled before we assert on it.
Fixes molecule-core#22.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
