CA-269642: Revert snapshot should clean up VUSBs
CA-269642: Revert snapshot should clean up VUSBs

1. Need to clean up VUSBs when reverting snapshot.

Signed-off-by: Taoyong Ding <2db94b36ac4630e45fb205c4dd3ab31219616507@citrix.com>

srowe/xen-api,srowe/xen-api,srowe/xen-api,srowe/xen-api,srowe/xen-api