I think that mock superstructure is intended for testing the electronics and internal layout of the Liaoning. Liaoning is still a work in progress, testing all aspects of carrier design and operating practices with which the Chinese had no prior experience. She is far from truly operational, if she ever would be, and that mock island is supporting her.
The new indigenous carrier will take about 5 years to complete. I bet long before 5 years is up, that mock superstructure would be dismantled and replaced with a different mockup to test the same for the new carrier.