Calico: set IP=autodetect so preempted nodes learn new IP

With preemptible nodes, a cluster node (with a given hostname) can
boot the first time with IP1, then be preempted and boot again with
different IP2.

With IP="", Calico will autodetect IP1 on first boot, but will not
perform autodetection on subsequent boots and so will not release IP1
and detect IP2 instead.

With IP=autodetect, Calico will perform autodetection on all boots,
which is what we want.

cluster/addons/calico-policy-controller/calico-node-daemonset.yaml

@@ -107,7 +107,7 @@ spec:
             - name: USE_POD_CIDR
               value: "true"
             - name: IP
-              value: ""
+              value: "autodetect"
             - name: NO_DEFAULT_POOLS
               value: "true"
             - name: NODENAME