Fix ansible-lint E502 for test playbooks.

This patch adds 'name' to all test playbook tasks that did not
have it, fixing ansible-lint's error 'unnamed-task'.

tests/user/test_users_present_slice.yml

@@ -13,7 +13,8 @@
   - name: Include users.json
     include_vars:
       file: users.json
-  - debug:
+  - name: Size of users slice.
+    debug:
       msg: "{{ users | length }}"
   - name: Users present
     ipauser: