There is no such word as 'shangy' in English. It has no meaning.
If 'Shangywood' is a term based on 'Hollywood', to refer to the Chinese film industry, I'd presume that it is a made-up word suggesting the name of the Chinese city 'Shanghai' : Shanghai-wood --> 'Shangywood'.
By the way, you shouldn't be surprised that this has no meaning. The capital 'S' tells you that this is a name, and names in English are generally not meaningful.