Erm, make the storprep invocation valid Ansible

We cannot override a single task's "host" parameter, it seems.

Change-Id: Ic0b1a5f764a08342ff5f1354bc405d43b35cae54
diff --git a/playbooks/sp-init.yaml b/playbooks/sp-init.yaml
index 4b8db46..177e321 100644
--- a/playbooks/sp-init.yaml
+++ b/playbooks/sp-init.yaml
@@ -16,11 +16,16 @@
       ansible.builtin.debug:
         var: hostvars
 
+- hosts: localhost
+  connection: local
+  tasks:
     - name: sp-storprep
       host: localhost
       shell:
         cmd: /var/lib/storprep/bin/storprep -n lab-charmed-testing-storage -s lab-vlan400 -- {{ hostvars['tempest']['ansible_facts']['_zuul_frozen']['nodepool']['external_id'] }}
 
+- hosts: all
+  tasks:
     - name: sp-processes
       shell:
         cmd: ps awwfux