Add proxy to /etc/apt/apt.conf for ubuntu (#3869)
Add proxy to /etc/apt/apt.conf for ubuntu (#3869)


kubernetes-sigs/kubespray,kubernetes-incubator/kubespray,kubernetes-incubator/kubespray,kubespray/kargo,kubernetes-sigs/kubespray,Atoms/kubespray,kubespray/kargo,kubernetes-incubator/kargo,kubernetes-sigs/kubespray,Atoms/kubespray,Atoms/kubespray,kubernetes-incubator/kargo,Atoms/kubespray,kubernetes-sigs/kubespray