[3.0-Triple] Application service discovery had broken down because of consumerModel's NPE in TripleClientHandler

[plusmancn]

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Because of TripleClientHandler working in a new thread, The line url.getServiceMode doesn't work in TripleClientHandler with InstanceAddressURL when we try to use application-service-discovery.

// => org.apache.dubbo.rpc.protocol.tri.TripleClientHandler#writeRequest
private void writeRequest(ChannelHandlerContext ctx, final Request req, final ChannelPromise promise) {
    final RpcInvocation inv = (RpcInvocation) req.getData();
    final URL url = inv.getInvoker().getUrl();
    // Here will throw NPE
    ConsumerModel consumerModel = (ConsumerModel) url.getServiceModel();
    // ......
}

See InstanceAddressURL:

// => org.apache.dubbo.registry.client.InstanceAddressURL#getServiceModel
public ServiceModel getServiceModel() {
    return RpcContext.getServiceContext().getConsumerUrl().getServiceModel();
}

// => org.apache.dubbo.rpc.RpcContext
private static final InternalThreadLocal<RpcServiceContext> SERVICE_CONTEXT = new InternalThreadLocal<RpcServiceContext>() {
    @Override
    protected RpcServiceContext initialValue() {
        return new RpcServiceContext();
    }
};