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/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 {