OTel - Log signal for routed requests to unknown service id

When APIML could not route a request due to unknown service id or there is no instance available, produce a log signal with attributes:

• time of event (timestamp)
• apiml url path (url.path)
• apiml url scheme (url.scheme)
• apiml http method (http.request.method)
• apiml response code (http.response.status_code)
• apiml error type (error.type)
• apiml error message (error.message)
• user id (user.id)
• service id (service.id)

Note: check the feature for attributes meaning.

Note: Requires implementing a WebFilter because if the route does not match, GlobalFilter is not executed

Acceptance criteria:

• When a request is made to a valid gateway URL but an unknown Service ID (or a service that is down):
  • The log is generated.
  • http.response.status_code records 404 or 503.
  • service.id records the attempted service name (if parsable) or "unknown".
  • error.type:
    • Service not onboarded
    • Service instance not available
• Acceptance tests
• Documentation updated

Start by reviewing the existing feature that defines the log attributes, then trace the gateway routing path and the WebFilter needed when no route matches. Use the acceptance-test area to cover unknown or unavailable services and verify the status, service, and error fields. Done includes the requested log signal, acceptance tests, and updated documentation.