You only build as much of the world as is necessary to tell your story. The story is the thing, not the worldbuilding.
You (as the author) can think up all kinds of details and backstory for everything and keep that all in your notes to add to your story for color, but dumping all of the details in the story will just get in the way.
You've surely heard of Chekhov's gun. Apply that principle to your worldbuilding.
If some detail of your world isn't relevant to the story, leave it out. Every word you spend building your world is a word less to spend on telling your story.
Consider Impressionism in comparison to Realism in art.
Impressionists try to reduce the picture to the minimum needed to accurately portray the subject of the painting. Realists try to accurately portray every detail in the scene, no matter how small.
In a short story or novella, you need to lean heavily towards the impressionistic side.
This is realism:
That is The Arnolfini Portrait from Arnold van Eyck.
You can zoom in and see incredible detail. Between the man and the woman is a small, round mirror. You can get up close to it, and see that the painter himself is visible in the background of the mirror reflection:
In comparion, this is impressionism:
That's The Beach at Trouville by Claude Monet
When viewed from a slight distance, it looks like a fairly detailed painting.
When viewed up close, you can see that it is not detailed at all.
It gives the impression of the scene - a reduced view that conveys the heart of the composition without clutter.
Your short story or novella must follow the impressionist style - convey the heart of the composition without over loading the reader.
You only have so many words to "spend" in a short story or novella. You must choose whether to spend them on worldbuilding (extraneous detail) or story telling (the heart of the composition.)