CA-223505 detach a VM's network (PVS) when migrating away from a host
CA-223505 detach a VM's network (PVS) when migrating away from a host

The detach is part of xapi_vm_migrate:{pool_migrate, migrate_send}.
Previously PVS resources would not be freed because the network was
not explicitly detached.

Signed-off-by: Christian Lindig <4f88b50bc9dba63c9a7d9e208d4b3ac6f1a52800@citrix.com>

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