Chronos user-case notebook should be refactor to use TSDataset

[TheaperDeng]

Some functions and customized code is used in Zouwu user-case notebook. Including Those can be easily changed to built-in codes in zouwu: metrics Those need to be included in zouwu: isolated rolling and plot functions

This issue is related to or part of issue intel-analytics/analytics-zoo-internal#556

[shanyu-sys]

For network_traffic_model_forecasting notebook,

• [ ] Replace gen_dataset_matrix with zouwu API. Note that you need to modify the roll data function in zouwu feature for better support.
• [ ] Replace the scaling code and unscale with zouwu API. You need to modify the scale and uncale function in zouwu feature for better support.
• [ ] replace the data fill code (ffill) with zouwu impute API.
• [ ] replace sMAPE with automl metric. You can find the definition of smape here