Fix log filtering for grpc errors. (#5712)
Fix log filtering for grpc errors. (#5712)

We had in place some filtering for grpc errors that we consider
spurious, but that filtering was broken. This change ensures the
filtering gets called regardless of which of the various error/warning
methods grpc calls. This removes a lot of unnecessary red from our
integration test output.
jcjones/boulder,jcjones/boulder,jsha/boulder,jsha/boulder,jcjones/boulder,letsencrypt/boulder,jsha/boulder,letsencrypt/boulder,letsencrypt/boulder,jcjones/boulder