Inconsistent naming of pois / locations

[david-venhoff]

Describe the Bug

We have a model called POI, which is sometimes referred to using poi and sometimes referred to using ___location (For example, the event model stores ___location, but region uses pois).
This can be confusing and is inconsistent. Instead, we should decide for one name and stick to it.

As far as I know, in the codebase we mostly use poi, while we mostly use ___location in the ui. However, there are exceptions for both.