Gather minimal facts to use ansible_distribution

We tried to use `ansible_distribution` variable for localhost but we never
gathered facts for it, so in real deployments we always fallback
to rescue block.

Change-Id: I7a01cb019a32c7d2b0fa8a326826ab2cf288939a

scripts/get-ansible-role-requirements.yml

@@ -19,6 +19,10 @@
   user: root
   gather_facts: false
   tasks:
+    - name: Gather minimal facts
+      setup:
+        gather_subset: '!all'
+
     - name: Remove target directory if required
       file:
         path: "{{ item.path | default(role_path_default) }}/{{ item.name | default(item.src | basename) }}"