api_endpoint in `snippets` methods can be reconstructed from the `location` argument.

As per the title, `api_endpoint` can be reconstructed from the `location` argument. This led to problems because if the model is deployed elsewhere the requests fail. Additionally, the `api_endpoint` meaning is a bit opaque since a user could assume that everything should work even if `location` and `api_endpoint` point to different regions (i.e. the endpoint is just a gateway).