Pause recovery when it ends with Shutdown

In the current design, when recovery ends with Shutdown, it will
continue to execute commands repeatedly in the loop body, after it sets
a "Shutdown" property. That may lead to some competition between the
shutdown process and recovery command work, and then cause some
problems.

So, pause recovery when it ends with Shutdown, like it ending with
Reboot.

Change-Id: I57dfef70e7b8d600af3a3f2c0199f14d5a0e9916