FIx error in task "Make RAID0 device" on Ansible 2.9

Starting Ansible 2.9, task "Make RAID0 device" (only active when using SSD disks on Google Cloud) can fail with this error:

```
The conditional check 'localssd_all_devices_count > 0' failed. The error was: Unexpected templating type error occurred on ({% if localssd_all_devices_count > 0 %} True {% else %} False {% endif %}): '>' not supported between instances of 'AnsibleUnsafeText' and 'int'
```

This rather ad-hoc fix coerces the "unsafe text" into an integer.
There might be more issues like this with Ansible 2.9, if anything
that's inputed from external processes is marked as "unsafe" and needs
to somehow be washed before using in conditionals and templates.

Thanks to X. Y. Han for reporting the issue and testing the fix!

elasticluster/share/playbooks/roles/google-local-ssd/tasks/main.yml

@@ -41,20 +41,20 @@
         {{ localssd_all_devices|join(" ") }}
   args:
     creates: '/dev/md/google-local-ssd'
-  when: 'localssd_all_devices_count > 0'
+  when: 'localssd_all_devices_count|int > 0'
 
 - name: Format RAID0 device
   filesystem:
     dev: '/dev/md/google-local-ssd'
     fstype: ext4
     opts: '-m 0 -L /srv/google-local-ssd'
-  when: 'localssd_all_devices_count > 0'
+  when: 'localssd_all_devices_count|int > 0'
 
 - name: Make mountpoint
   file:
     dest: '/srv/google-local-ssd'
     state: directory
-  when: 'localssd_all_devices_count > 0'
+  when: 'localssd_all_devices_count|int > 0'
 
 - name: Mount local SSD filesystem
   mount:
@@ -63,4 +63,4 @@
     state: mounted
     fstype: ext4
     opts: 'rw,nofail'
-  when: 'localssd_all_devices_count > 0'
+  when: 'localssd_all_devices_count|int > 0'