Automatic merge from submit-queue (batch tested with PRs 45200, 45203)
Allow certificate manager to be initialized with no certs.
Adds support to the certificate manager so it can be initialized with no
certs and only a connection to the certificate request signing API. This
specifically covers the scenario for the kubelet server certificate,
where there is a request signing client but on first boot there is no
bootstrapping or local certs.
f263fbe5e1