During reconciliation, the bootstrap provider copies the content from the secret provided by Kamaji, named `<cluster>-admin-kubeconfig` into a `cluster-info` configmap of tenant cluster, which then used by kubeadm to join nodes.
This change introduces a new annotation, `kamaji.clastix.io/kubeconfig-secret-key`, for the TenantControlPlane resource. This annotation instructs kamaji to read the kubeconfig from a specific key (the default one is super-admin.conf).
Example:
```
kamaji.clastix.io/kubeconfig-secret-key: super-admin.svc
```
This will instruct the system to use `super-admin.svc` a kubeconfig with a local service FQDN (introduced by https://github.com/clastix/kamaji/pull/403).
Signed-off-by: Andrei Kvapil <kvapss@gmail.com>
