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>)

.gitlab-ci.yml

@@ -10,6 +10,7 @@ variables:
   FAILFASTCI_NAMESPACE: 'kargo-ci'
   GITLAB_REPOSITORY: 'kargo-ci/kubernetes-sigs-kubespray'
   ANSIBLE_FORCE_COLOR: "true"
+  ANSIBLE_STDOUT_CALLBACK: "debug"
   MAGIC: "ci check this"
   GS_ACCESS_KEY_ID: $GS_KEY
   GS_SECRET_ACCESS_KEY: $GS_SECRET