[RBD_BKP] remove local snaps when removing remote snapshot
[RBD_BKP] remove local snaps when removing remote snapshot

The local snaps are useless after remote snap been deleted.

ZhangZhenhua/eontools,eoncloud-dev/eontools,eoncloud-dev/eontools,ZhangZhenhua/eontools,eoncloud-dev/eontools,ZhangZhenhua/eontools