The default polling delay of 1 minute results in very long delays when
an Azure Disk is attached to a node. It gets worse as go-autorest
doubles the default delay to 2 minutes.
Please see: https://github.com/kubernetes/kubernetes/issues/35180#issuecomment-273085063
Only the PollingDelay for VirtualMachinesClient is modified here to
avoid too much pressure on Azure quotas.
