If available, ensure that Analytics' regions are "us" and "de" (not "eu")

We've recently discovered that at least one API client was exposing "eu" as a
valid region for the Analytics client implementation, which is wrong. Only the
following regions are available at the moment to the Analytics client:

- "us"
- "de"

Start by locating the Analytics client implementation and the code that defines or validates its available regions. Confirm that only "us" and "de" are accepted, and check the relevant existing tests or add coverage so the obsolete "eu" region is no longer exposed.

Written by the indexing model from the issue text.