additionalTrustBundle IsCA check to warn instead of drop

When using `additionalTrustBundle` accept v1 certificates and non-CA
certificates. In place of the drop warn user that the
certificate provided is either v1 or a non-CA certificate.

pkg/asset/manifests/additionaltrustbundleconfig.go

@@ -115,9 +115,11 @@ func parseCertificates(certificates string) (map[string]string, error) {
 		}
 
 		if cert.IsCA {
-			sb.WriteString(string(pem.EncodeToMemory(block)))
+			logrus.Warn("The additionalTrustBundle certificate is either not v3 or a certificate authority")
 		}
 
+		sb.WriteString(string(pem.EncodeToMemory(block)))
+
 		if len(rest) == 0 {
 			break
 		}