CP-18251: Remove detach in attach as the detach should already happens when detach_attached_updates
CP-18251: Remove detach in attach as the detach should already happens when detach_attached_updates

Signed-off-by: Cheng Zhang <f157832f2f1df5a7c962d3abb092f6b1ea020882@citrix.com>

thomassa/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api,thomassa/xen-api,thomassa/xen-api,euanh/xen-api,thomassa/xen-api,euanh/xen-api,Frezzle/xen-api,euanh/xen-api,srowe/xen-api,thomassa/xen-api,srowe/xen-api,euanh/xen-api,srowe/xen-api,Frezzle/xen-api,Frezzle/xen-api,thomassa/xen-api,Frezzle/xen-api,srowe/xen-api