heal: Remove .healing.bin when all ES drives are healing (#19846)

In the very rare case when all drives in a erasure set need to be healed,
remove .healing.bin from all drives, otherwise it will be stuck in a
loop

Also, fix a unit test that fails sometimes due to wrong test.

cmd/background-newdisks-heal-ops.go

@@ -453,10 +453,6 @@ func healFreshDisk(ctx context.Context, z *erasureServerPools, endpoint Endpoint
 
 	healingLogEvent(ctx, "Healing of drive '%s' is finished (healed: %d, skipped: %d, failed: %d).", disk, tracker.ItemsHealed, tracker.ItemsSkipped, tracker.ItemsFailed)
 
-	if len(tracker.QueuedBuckets) > 0 {
-		return fmt.Errorf("not all buckets were healed: %v", tracker.QueuedBuckets)
-	}
-
 	if serverDebugLog {
 		tracker.printTo(os.Stdout)
 		fmt.Printf("\n")

cmd/global-heal.go

@@ -530,7 +530,16 @@ func (er *erasureObjects) healErasureSet(ctx context.Context, buckets []string,
 	tracker.setObject("")
 	tracker.setBucket("")
 
-	return retErr
+	if retErr != nil {
+		return retErr
+	}
+
+	// Last sanity check
+	if len(tracker.QueuedBuckets) > 0 {
+		return fmt.Errorf("not all buckets were healed: %v", tracker.QueuedBuckets)
+	}
+
+	return nil
 }
 
 func healBucket(bucket string, scan madmin.HealScanMode) error {