Remove stale instance_double of the deleted CloudConnector::BaseAvailableServiceData in the AI Gateway client spec

Summary

ee/spec/lib/gitlab/llm/ai_gateway/client_spec.rb line 14 defines:

let(:service) { instance_double(CloudConnector::BaseAvailableServiceData, name: :test) }

CloudConnector::BaseAvailableServiceData no longer exists anywhere in the repository. It went away with the CloudConnector::AvailableServices cleanup (see !192366 (merged) and the CHANGELOG entry "Remove add_on_purchases from AvailableServices"). service is not referenced anywhere else in the spec file.

Because let is lazy, the missing constant is never resolved and the spec passes today. The first example that references service will fail with NameError (and instance_double of a non-existent class would fail verification as well), so this is dead code with a latent failure attached.

Proposal

Delete the let(:service) line. No behaviour change.

Verification

• grep -rn BaseAvailableServiceData across the tree returns only this line.
• grep -n '\bservice\b' ee/spec/lib/gitlab/llm/ai_gateway/client_spec.rb returns only line 14.

Found on 2026-09-11 while mapping the Cloud Connector code paths for a new backend service.