NotMyVBucket tries to use custom serializer to read updated bucket config

If an application uses a custom serializer and receives a NotMyVBucket response, the client tries to use the custom serializer to read the BucketConfig that is in the response body. This should instead use the default JSON serializer.

This was raised on behalf of this forum post
https://forums.couchbase.com/t/errors-in-the-custom-serializer-after-a-rebalance/13243