Problem

The method Repository#gitlab_ci_yml_for is used in many places as well as Project#ci_config_for. Both methods are nowadays ambiguous since the SSoT is Ci::ProjectConfig because a project can define the ci_config_path to be an external project or a URL.

If for the use case at hand we specifically want the local CI config file we should first check if it exists and then use Repository#blob_data_at.

For use cases where we need the content of the actual CI yaml, regardless of the location, we should use Ci::ProjectConfig.

Proposal

deprecate and remove Repository#gitlab_ci_yml_for and Project#ci_config_for methods.