fix apt-get update might be failed in Ubuntu. We need to disable Ubuntu unattended-upgrades.
fix apt-get update might be failed in Ubuntu. We need to disable
Ubuntu unattended-upgrades.

mingjian2049/zstack-utility,live4thee/zstack-utility,zstackio/zstack-utility,zstackio/zstack-utility,live4thee/zstack-utility,zstackorg/zstack-utility,mingjian2049/zstack-utility,zstackorg/zstack-utility,mrwangxc/zstack-utility,zstackio/zstack-utility,live4thee/zstack-utility,mrwangxc/zstack-utility,zstackorg/zstack-utility,mrwangxc/zstack-utility,mingjian2049/zstack-utility