Migrate AmazonQ away from AvailableServices

• Refactor ee/app/services/ai/amazon_q/amazon_q_trigger_service.rb to use ::CloudConnector::Tokens.get(unit_primitive: unit_primitive)
• Refactor ee/lib/ai/amazon_q/identity_provider_payload_factory.rb to use ::CloudConnector::Tokens.get(unit_primitive: unit_primitive)

Replace and remove any occurrences of service/service_name, and use unit_primitive instead in this files