Comment 2 for bug 1734725

I agree that either:
 a) We're in a cloud where we know the credentials aren't region specific, so we can just ignore the region of the credential
 b) We're in a cloud where the credentials are per region, in which case we should refuse if we don't have a credential for the region the user asked for.
 c) User asked to create a model in a given cloud, but not in a particular region, then we could use the region from the credential

We should definitely not be quietly changing the region.