auth: Make luci-go services trust signatures produced by the token server.

server/auth/delegation/checker_test.go

Index: server/auth/delegation/checker_test.go
diff --git a/server/auth/delegation/checker_test.go b/server/auth/delegation/checker_test.go
index 2756690a279f59bf891035de992af326adf53630..32364928cd725f3fc1cad239c039e3d012689773 100644
--- a/server/auth/delegation/checker_test.go
+++ b/server/auth/delegation/checker_test.go
@@ -188,7 +188,7 @@ func newFakeTokenMinter() *fakeTokenMinter {
 	}
 }
 
-func (f *fakeTokenMinter) GetAuthServiceCertificates(c context.Context) (*signing.PublicCertificates, error) {
+func (f *fakeTokenMinter) GetCertificates(c context.Context, id identity.Identity) (*signing.PublicCertificates, error) {
 	return f.signer.Certificates(c)
 }