Consolidate CC access check logic for ga features

doc/development/cloud_connector/index.md

ee/app/models/concerns/ai/user_authorizable.rb

ee/app/policies/ee/ci/build_policy.rb

ee/app/policies/ee/global_policy.rb

ee/app/policies/ee/merge_request_policy.rb

ee/app/policies/ee/project_policy.rb

ee/app/policies/vulnerability_policy.rb

ee/lib/api/code_suggestions.rb

ee/lib/gitlab/llm/utils/ai_features_catalogue.rb

ee/lib/gitlab/llm/utils/user_authorizer.rb

ee/spec/lib/gitlab/llm/utils/user_authorizer_spec.rb

ee/spec/models/concerns/ai/user_authorizable_spec.rb

ee/spec/policies/ci/build_policy_spec.rb

ee/spec/policies/global_policy_spec.rb

ee/spec/policies/merge_request_policy_spec.rb

ee/spec/policies/vulnerability_policy_spec.rb

ee/spec/requests/api/code_suggestions_spec.rb

...raphql/mutations/projects/generate_commit_message_spec.rb

...uests/api/graphql/user_code_suggestions_available_spec.rb