Problem:
Only the client CA is passed to the kube-controller-manager and
therefore CSRs with the signer name "kubernetes.io/kubelet-serving" are
signed with the client CA. Serving certificates must be signed with the
server CA otherwise e.g. "kubectl logs" fails with the error message
"x509: certificate signed by unknown authority".

Solution:
Instead of providing only one CA via the kube-controller-manager
parameter "--cluster-signing-cert-file", the corresponding CA for every
signer is set with the parameters
"--cluster-signing-kube-apiserver-client-cert-file",
"--cluster-signing-kubelet-client-cert-file",
"--cluster-signing-kubelet-serving-cert-file", and
"--cluster-signing-legacy-unknown-cert-file".
Signed-off-by: Siegfried Weber <mail@siegfriedweber.net>
(cherry picked from commit e77fd182)