CI: Use the debug stdout callback instead of manual debug

This display in a readable (by humans) way the result of most tasks, and
should be way more readable that what we have now, which is frequently a
bunch of unreadable json.

+ some small fixes (using delegated_to instead of when
  <control_plane_host>)

tests/testcases/010_check-apiserver.yml

@@ -13,9 +13,6 @@
     delay: 5
     until: apiserver_response is success
 
-  - debug:  # noqa name[missing]
-      msg: "{{ apiserver_response.json }}"
-
   - name: Check API servers version
     assert:
       that: