chore: fix error message for JournalingBlobWriteSessionConfig (#2752)

Now properly reports grpc only rather than incorrect http only.

google-cloud-storage/src/main/java/com/google/cloud/storage/JournalingBlobWriteSessionConfig.java

@@ -215,7 +215,7 @@ public WritableByteChannelSession<?, BlobInfo> writeSession(
 
         return new JournalingUpload<>(session, start);
       } else {
-        return CrossTransportUtils.throwHttpJsonOnly(BlobWriteSessionConfigs.class, "journaling");
+        return CrossTransportUtils.throwGrpcOnly(BlobWriteSessionConfigs.class, "journaling");
       }
     }