Auth v2: Complicated/confusing error message when RequestServiceAccessToken specifies non-existing URL

[reinkrul]

Server responds with 404, leading to the following log:

{"error":"failed to retrieve remote OAuth Authorization Server metadata: invalid client call\nserver returned HTTP 404 (expected: 200)","level":"warning","module":"Auth/iam","msg":"RequestServiceAccessToken failed","operation":"RequestServiceAccessToken","operationID":"RequestServiceAccessToken","requestURI":"/internal/auth/v2/zbj-tst/request-service-access-token","time":"2025-02-04T10:22:14Z","user":null}

invalid client call is a weird message