add option to use calico with azure when using calico in vxlan (#7300)

roles/kubernetes/preinstall/tasks/0020-verify-settings.yml

@@ -38,10 +38,13 @@
 
 - name: Stop if incompatible network plugin and cloudprovider
   assert:
-    that: kube_network_plugin != 'calico'
-    msg: "Azure and Calico are not compatible. See https://github.com/projectcalico/calicoctl/issues/949 for details."
+    that:
+      - calico_ipip_mode == 'Never'
+      - calico_vxlan_mode in ['Always', 'CrossSubnet']
+    msg: "When using cloud_provider azure and network_plugin calico calico_ipip_mode must be 'Never' and calico_vxlan_mode 'Always' or 'CrossSubnet'"
   when:
     - cloud_provider is defined and cloud_provider == 'azure'
+    - kube_network_plugin == 'calico'
     - not ignore_assert_errors
 
 - name: Stop if unsupported version of Kubernetes