burnin: move start_stop at the end

Traditionally the start/stop test was the last, so move it back to there
(added as last option in commit 854).

Reviewed-by: amishchenko

tools/burnin

@@ -659,12 +659,12 @@ class Burner(object):
       if opts.do_activate_disks:
         self.ActivateDisks()
 
-      if opts.do_startstop:
-        self.StopStart()
-
       if opts.rename:
         self.Rename()
 
+      if opts.do_startstop:
+        self.StopStart()
+
       has_err = False
     finally:
       if has_err: