tasks: Always create the machines.raw file

The machines.raw file is only created if the 'machinectl set-limit'
command returns non-zero exit code. However, this file is expected to
be present later on so we need to make sure that we create without
taking the 'machinectl' exit code into consideration.

Fixes the following problem:

Change-Id: If96c870d317bc7a024169ffd04e8f4c10003ba74
fatal: [localhost]: FAILED! => {"changed": false, "msg": "Device /var/lib/machines.raw not found."}
Signed-off-by: Kevin Carter <kevin.carter@rackspace.com>

tasks/nspawn_volume.yml

@@ -19,25 +19,16 @@
   changed_when: false
   register: machinectl_mount
 
-- name: Create systemd sparse file
-  block:
-    - name: Set volume size
-      shell: machinectl set-limit {{ nspawn_host_machine_volume_size }}
-      changed_when: false
-      register: machines_create
-      args:
-        executable: /bin/bash
-      tags:
-        - skip_ansible_lint
-  rescue:
-    - name: Create volume file (fallback)
-      shell: |
-        truncate -s '>{{ nspawn_host_machine_volume_size }}' /var/lib/machines.raw
-      register: machines_create
-      args:
-        executable: /bin/bash
-      tags:
-        - skip_ansible_lint
+- name: Set the machinectl limit
+  shell: |
+    machinectl set-limit {{ nspawn_host_machine_volume_size }}
+    truncate -s '>{{ nspawn_host_machine_volume_size }}' /var/lib/machines.raw
+  changed_when: false
+  register: machines_create
+  args:
+    executable: /bin/bash
+  tags:
+    - skip_ansible_lint
 
 - name: Systemd machinectl mount
   block: