test/azure: kubeadm does not pass

[tormath1]

Description

kubeadm kola test fails on Azure. It's currently excluded from the tests (flatcar/mantle#174)

Additional information

From an initial investigation, there are a lot of spamming related to FlexVolume on the controller node:

May 17 07:54:56.412459 kubelet[2807]: E0517 07:54:56.412399    2807 plugins.go:748] Error dynamically probing plugins: Error creating Flexvolume plugin from directory nodeagent~uds, skipping. Error: unexpected end of JSON input
May 17 07:54:56.412698 kubelet[2807]: E0517 07:54:56.412681    2807 driver-call.go:266] Failed to unmarshal output for command: init, output: "", error: unexpected end of JSON input

some warnings too:

May 17 07:57:30.093286 kubelet[2807]: W0517 07:57:30.087905    2807 reflector.go:436] k8s.io/client-go/informers/factory.go:134: watch of *v1.CSIDriver ended with: an error on the server ("unable to decode an event from the watch stream: http2: client connection force closed via ClientConn.Close") has prevented the request from succeeding
May 17 07:57:30.093286 kubelet[2807]: W0517 07:57:30.087926    2807 reflector.go:436] object-"calico-system"/"cni-config": watch of *v1.ConfigMap ended with: an error on the server ("unable to decode an event from the watch stream: http2: client connection force closed via ClientConn.Close") has prevented the request from succeeding

from the worker node, we can see that kubeadm seems to fail to join the cluster.