fix: generate config with only globalImageRegistryMirror set

[dkoshkin]

Follow up to #359

I noticed that when the only setting globalImageRegistryMirror without imageRegistries that the credential provider configs were not being generated.

Tested locally and verified in the Docker container :

kubectl get kubeadmconfig.bootstrap.cluster.x-k8s.io/docker-quick-start-helm-addon-cilium-dgz8d-dk7c5 -o yaml | grep "path:"
        audit-log-path: /var/log/audit/kube-apiserver-audit.log
    path: /etc/kubernetes/audit-policy/apiserver-audit-policy.yaml
    path: /etc/konvoy/install-kubelet-credential-providers.sh
    path: /etc/kubernetes/image-credential-provider-config.yaml
    path: /etc/kubernetes/dynamic-credential-provider-config.yaml
    path: /etc/kubernetes/static-image-credentials.json
    path: /etc/containerd/certs.d/_default/hosts.toml

root@docker-quick-start-helm-addon-cilium-md-0-7zv45-plbrx-wv86j:/# ls -lat /etc/kubernetes/
total 44
drwxr-xr-x 1 root root 4096 Feb 14 23:02 ..
drwxr-xr-x 1 root root 4096 Feb 14 22:59 .
drwxr-xr-x 4 root root 4096 Feb 14 22:59 node-feature-discovery
-rw------- 1 root root 1911 Feb 14 22:59 kubelet.conf
drwxr-xr-x 2 root root 4096 Feb 14 22:59 pki
drwxr-xr-x 2 root root 4096 Feb 14 22:59 image-credential-provider
-rw------- 1 root root  248 Feb 14 22:59 static-image-credentials.json
-rw------- 1 root root  694 Feb 14 22:59 dynamic-credential-provider-config.yaml
-rw------- 1 root root  383 Feb 14 22:59 image-credential-provider-config.yaml
drwxr-xr-x 2 root root 4096 May 25  2023 manifests

[jimmidyson]

Thank you for updating the comments! Now I understand! 😅