avoid race conditions during render cert creation

This bug is to get the fixes from another PR in:
https://github.com/openshift/cluster-etcd-operator/pull/1235

Namely that we were relying on a race condition in the fake library to sync the informer and client lister to generate the certificates.
This fix entails a lister that directly goes via the client to avoid using the informer.

4.16.0    

always, when reordering the statements in the code    

Reodering the code blocks as in https://github.com/openshift/cluster-etcd-operator/pull/1235/files#diff-273071b77ba329777b70cb3c4d3fb2e33bc8abf45cb3da28cbee512d591ab9ee 

will immediately expose the race condition in unit tests.