r/kubelet: Ensure iscsi service is running

The _iscsi.socket_ unit gets enabled by default with the
_iscsi-initiator-utils_ package is installed, but it won't start
automatically until the next boot.  Without this service running,
Longhorn volumes will not be able to attach to the node, so we need to
explicitly ensure it is running before any workloads are assigned to the
node.

roles/kubelet/tasks/main.yml

@@ -112,3 +112,16 @@
     enabled: true
   tags:
   - service
+
+- name: ensure iscsi socket is enabled
+  systemd:
+    name: iscsid.socket
+    enabled: true
+  tags:
+  - service
+- name: ensure iscsi socket is active
+  systemd:
+    name: iscsid.socket
+    state: started
+  tags:
+  - service